Calculus Volume 2
Calculus Volume 2
17th Edition
ISBN: 9781938168062
Author: Gilbert Strang, Edwin Jed Herman
Publisher: OpenStax
bartleby

Concept explainers

Minimization
In mathematics, traditional optimization problems are typically expressed in terms of minimization. When we talk about minimizing or maximizing a function, we refer to the maximum and minimum possible values of that function. This can be expressed in ter…
Maxima and Minima
The extreme points of a function are the maximum and the minimum points of the function. A maximum is attained when the function takes the maximum value and a minimum is attained when the function takes the minimum value.
Derivatives
A derivative means a change. Geometrically it can be represented as a line with some steepness. Imagine climbing a mountain which is very steep and 500 meters high. Is it easier to climb? Definitely not! Suppose walking on the road for 500 meters. Which …
Concavity
In calculus, concavity is a descriptor of mathematics that tells about the shape of the graph. It is the parameter that helps to estimate the maximum and minimum value of any of the functions and the concave nature using the graphical method. We use the …
bartleby

Videos

Textbook Question
Book Icon
Chapter 7.4, Problem 218E

For the following exercises, find the length of the curve over the given interval.

218. r = 6 on the interval 0 ≤ θ ≤ π 2

Expert Solution & Answer
Check Mark

Want to see the full answer?

Check out a sample textbook solution
Blurred answer
Previous
Chapter 7.4, Problem 217E
Next
Chapter 7.4, Problem 219E

Chapter 7 Solutions

Calculus Volume 2

Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - The Witch of Agnesi Many plane curves in...Ch. 7.1 - Travels with My Ant: The Curtate and Prolate...
Ch. 7.1 - Travels with My Ant: The Curtate and Prolate...Ch. 7.1 - Travels with My Ant: The Curtate and Prolate...Ch. 7.1 - Travels with My Ant: The Curtate and Prolate...Ch. 7.1 - Travels with My Ant: The Curtate and Prolate...Ch. 7.1 - For the following, exercises, sketch the curves...Ch. 7.1 - For the following, exercises, sketch the curves...Ch. 7.1 - For the following, exercises, sketch the curves...Ch. 7.1 - For the following, exercises, sketch the curves...Ch. 7.1 - For the following exercises, eliminate the...Ch. 7.1 - For the following exercises, use technology (CAS...Ch. 7.1 - For the following exercises, use technology (CAS...Ch. 7.1 - For the following exercises, use technology (CAS...Ch. 7.1 - For the following exercises, use technology (CAS...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, sketch the parametric...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, convert the...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - For the following exercises, the pairs of...Ch. 7.1 - Show that x=h+rcosy=k+rsin represents the equation...Ch. 7.1 - Use the equations in the preceding problem to find...Ch. 7.1 - For the following Exercises, use a graphing...Ch. 7.1 - For the following Exercises, use a graphing...Ch. 7.1 - For the following Exercises, use a graphing...Ch. 7.1 - An airplane traveling horizontally at 100 m/s over...Ch. 7.1 - The trajectory of a bullet is given by...Ch. 7.1 - [T] Use technology to sketch the curve represented...Ch. 7.1 - [T] Use technology to sketch x=2tan(t),y=3sec(t),t...Ch. 7.1 - Sketch the curve known as all epitrochoid, which...Ch. 7.1 - [T] Use technology to sketch the spiral curve...Ch. 7.1 - [T] Use technology to graph the curve given by the...Ch. 7.1 - [T] Sketch the curve given by parametric equations...Ch. 7.2 - For the following exercises, each set of...Ch. 7.2 - For the following exercises, each set of...Ch. 7.2 - For the following exercises, each set of...Ch. 7.2 - For the following exercises, each set of...Ch. 7.2 - For the following exercises, determine the slope...Ch. 7.2 - For the following exercises, determine the slope...Ch. 7.2 - For the following exercises, determine the slope...Ch. 7.2 - For the following exercises, determine the slope...Ch. 7.2 - For the following exercises, determine the slope...Ch. 7.2 - For the following exercises, find all points on...Ch. 7.2 - For the following exercises, find all points on...Ch. 7.2 - For the following exercises, find all points on...Ch. 7.2 - For the following exercises, find all points on...Ch. 7.2 - For the following exercises, write the equation of...Ch. 7.2 - For the following exercises, write the equation of...Ch. 7.2 - For the following exercises, write the equation of...Ch. 7.2 - For x=sin(2t),y=2sint where 0t2 . Find all values...Ch. 7.2 - For x=sin(2t),y=2sint where 0t2 . Find all values...Ch. 7.2 - Find all points on the curve x=4cos(t),y=4sin(t)...Ch. 7.2 - Find dydx for x=sin(t),y=cos(t) .Ch. 7.2 - Find the equation of the tangent line to...Ch. 7.2 - For the curve x=4t,y=3t2 , find the slope and...Ch. 7.2 - For the parametric curve whose equation is...Ch. 7.2 - Find the slope and concavity for the curve whose...Ch. 7.2 - Find all points on the curve x=t+4,y=t33t at which...Ch. 7.2 - Find all points on the curve x=sec,y=tan at which...Ch. 7.2 - For the following exercises, find d2y/dx2 . 88....Ch. 7.2 - For the following exercises, find d2y/dx2 . 89....Ch. 7.2 - For the following exercises, find d2y/dx2 . 90....Ch. 7.2 - For the following exercises, find points on the...Ch. 7.2 - For the following exercises, find points on the...Ch. 7.2 - For the following exercises, find dy/dx at the...Ch. 7.2 - For the following exercises, find dy/dx at the...Ch. 7.2 - For the following exercises, find dy/dx at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, ?nd d2y/dx2 at the...Ch. 7.2 - For the following exercises, find d2y/dx2 at the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the arc length...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.2 - For the following exercises, find the area of the...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - In the following exercises, plot the point whose...Ch. 7.3 - For the following exercises, consider the polar...Ch. 7.3 - For the following exercises, consider the polar...Ch. 7.3 - For the following exercises, consider the polar...Ch. 7.3 - For the following exercises, consider the polar...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, the rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, find rectangular...Ch. 7.3 - For the following exercises, determine whether the...Ch. 7.3 - For the following exercises, determine whether the...Ch. 7.3 - For the following exercises, determine whether the...Ch. 7.3 - For the following exercises, determine whether the...Ch. 7.3 - For the following exercises, determine whether the...Ch. 7.3 - For the following exercises, describe the graph of...Ch. 7.3 - For the following exercises, describe the graph of...Ch. 7.3 - For the following exercises, describe the graph of...Ch. 7.3 - For the following exercises, describe the graph of...Ch. 7.3 - For the following exercises, convert the...Ch. 7.3 - For the following exercises, convert the...Ch. 7.3 - For the following exercises, convert the...Ch. 7.3 - For the following exercises, convert the...Ch. 7.3 - For the following exercises, convert the...Ch. 7.3 - For the following exercises, convert the polar...Ch. 7.3 - For the following exercises, convert the polar...Ch. 7.3 - For the following exercises, convert the polar...Ch. 7.3 - For the following exercises, convert the polar...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - For the following exercises, sketch a graph of the...Ch. 7.3 - [T] Use a graphing utility and sketch the graph of...Ch. 7.3 - [T] Use a graphing utility to graph r=11cos .Ch. 7.3 - [T] Use technology to graph r=esin()2cos(4) .Ch. 7.3 - [T] Use technology to plot r=sin(37) (use the...Ch. 7.3 - Without using technology, sketch the polar curve...Ch. 7.3 - [T] Use a graphing utility to plot r=sin for .Ch. 7.3 - [T] Use technology to plot r=e0.1 for 1010 .Ch. 7.3 - [T] There is a curve known as the “Black Hole.”...Ch. 7.3 - [T] Use the results of the preceding two problems...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the fallowing exercises, determine a definite...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find the area of the...Ch. 7.4 - For the following exercises, find a definite...Ch. 7.4 - For the following exercises, find a definite...Ch. 7.4 - For the following exercises, find a definite...Ch. 7.4 - For the following exercises, find a definite...Ch. 7.4 - For the following exercises, find the length of...Ch. 7.4 - For the following exercises, find the length of...Ch. 7.4 - For the following exercises, find the length of...Ch. 7.4 - For the following exercises, find the length of...Ch. 7.4 - For the following exercises, find the length of...Ch. 7.4 - For the following exercises, use the integration...Ch. 7.4 - For the following exercises, use the integration...Ch. 7.4 - For the following exercises, use the integration...Ch. 7.4 - For the following exercises, use the integration...Ch. 7.4 - For the following exercises, use the integration...Ch. 7.4 - For the fallowing exercises, use the familiar...Ch. 7.4 - For the fallowing exercises, use the familiar...Ch. 7.4 - For the fallowing exercises, use the familiar...Ch. 7.4 - For the following exercises, use the familiar...Ch. 7.4 - For the following exercises, use the familiar...Ch. 7.4 - For the following exercises, use the familiar...Ch. 7.4 - For the following exercises, use the familiar...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - For the following exercises, ?nd the slope of a...Ch. 7.4 - Find the paints on the interval at which the...Ch. 7.4 - For the cardioid r=1+sin , find the slope of the...Ch. 7.4 - For the following exercises, find the slope of the...Ch. 7.4 - For the following exercises, find the slope of the...Ch. 7.4 - For the following exercises, find the slope of the...Ch. 7.4 - For the following exercises, find the slope of the...Ch. 7.4 - For the following exercises, find the points at...Ch. 7.4 - For the following exercises, find the points at...Ch. 7.4 - For the following exercises, find the points at...Ch. 7.4 - For the following exercises, find the points at...Ch. 7.4 - For the following exercises, find the points at...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, determine the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, consider the...Ch. 7.5 - For the following exercises, ?nd a polar equation...Ch. 7.5 - For the following exercises, ?nd a polar equation...Ch. 7.5 - For the following exercises, ?nd a polar equation...Ch. 7.5 - For the following exercises, ?nd a polar equation...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following exercises, sketch the graph of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - For the following equations, determine which of...Ch. 7.5 - The mirror in an automobile headlight has a...Ch. 7.5 - A satellite dish is shaped like a paraboloid of...Ch. 7.5 - Consider the satellite dish of the preceding...Ch. 7.5 - A searchlight is shaped like a paraboloid of...Ch. 7.5 - Whispering galleries are rooms designed with...Ch. 7.5 - A person is standing 3 feet from the nearest wall...Ch. 7.5 - For the following exercises, determine the polar...Ch. 7.5 - For the following exercises, determine the pelar...Ch. 7.5 - For the following exercises, determine the pelar...Ch. 7.5 - For the following exercises, determine the polar...Ch. 7 - True or False? Justify your answer with a proof or...Ch. 7 - True or False? Justify your answer with a proof or...Ch. 7 - True or False? Justify your answer with a proof or...Ch. 7 - True or False? Justify your answer with a proof or...Ch. 7 - For the following exercises, sketch the parametric...Ch. 7 - For the following exercises, sketch the parametric...Ch. 7 - For the following exercises, sketch the parametric...Ch. 7 - For the following exercises, sketch the parametric...Ch. 7 - For the following exercises, sketch the polar...Ch. 7 - For the following exercises, sketch the polar...Ch. 7 - For the following exercises, find the polar...Ch. 7 - For the following exercises, find the polar...Ch. 7 - Fur the following exercises, find the equation of...Ch. 7 - Fur the following exercises, find the equation of...Ch. 7 - Fur the following exercises, find the equation of...Ch. 7 - For the following exercises, find the area of the...Ch. 7 - For the following exercises, find the area of the...Ch. 7 - For the following exercises, find the arc length...Ch. 7 - For the following exercises, find the arc length...Ch. 7 - For the following exercises, find the Cartesian...Ch. 7 - For the following exercises, find the Cartesian...Ch. 7 - For the following exercises, find the Cartesian...Ch. 7 - For the following exercises, determine the...Ch. 7 - For the following exercises, determine the...Ch. 7 - For the following exercises, determine the...Ch. 7 - Determine the Cartesian equation describing the...Ch. 7 - The C/1980 E1 comet was observed in 1980. Given an...

Additional Math Textbook Solutions

Find more solutions based on key concepts
At what points are the functions in Exercises 13–32 continuous? 29.

University Calculus: Early Transcendentals (4th Edition)

In Problem 19-26, write the function whose graph is the graph of y= x 3 , but is: Shifted up 4 units.

Precalculus

TRY IT YOURSELF 1 Find the mean of the points scored by the 51 winning teams listed on page 39.

Elementary Statistics: Picturing the World (7th Edition)

Version 2 of the Chain Rule Use Version 2 of the Chain Rule to calculate the derivatives of the following funct...

Calculus: Early Transcendentals (2nd Edition)

Two dice are thrown. Let E be the event that the sum of the dice is odd, let F be the event that at least one o...

A First Course in Probability (10th Edition)

CHECK POINT 1 Find a counterexample to show that the statement The product of two two-digit numbers is a three-...

Thinking Mathematically (6th Edition)

Knowledge Booster
Background pattern image
Math
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, subject and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Text book image
Discrete Mathematics and Its Applications ( 8th I...
Math
ISBN:9781259676512
Author:Kenneth H Rosen
Publisher:McGraw-Hill Education
Text book image
Mathematics for Elementary Teachers with Activiti...
Math
ISBN:9780134392790
Author:Beckmann, Sybilla
Publisher:PEARSON
Text book image
Calculus Volume 1
Math
ISBN:9781938168024
Author:Strang, Gilbert
Publisher:OpenStax College
Text book image
Thinking Mathematically (7th Edition)
Math
ISBN:9780134683713
Author:Robert F. Blitzer
Publisher:PEARSON
Text book image
Discrete Mathematics With Applications
Math
ISBN:9781337694193
Author:EPP, Susanna S.
Publisher:Cengage Learning,
Text book image
Pathways To Math Literacy (looseleaf)
Math
ISBN:9781259985607
Author:David Sobecki Professor, Brian A. Mercer
Publisher:McGraw-Hill Education
SEE MORE TEXTBOOKS
Finding Local Maxima and Minima by Differentiation; Author: Professor Dave Explains;https://www.youtube.com/watch?v=pvLj1s7SOtk;License: Standard YouTube License, CC-BY