Chapter 11.5, Problem 10WE

(a)

To determine

To Find: The circumference and area of circle.

Answer to Problem 10WE

  $C=25.1units$

  $A=50.2sq.units$

Explanation of Solution

Given: $diameter=8$ , use $\pi =3.14$

Given: $diameter=8$

  $\begin{array}{l}r=\frac{d}{2}\\ r=\frac{8}{2}\\ r=4\end{array}$

Circumference of a circle

  $\begin{array}{l}C=2\pi r\\ C=2(3.14)\left(4\right)\\ C=25.1units\end{array}$

Area of circle

  $\begin{array}{l}A=\pi r^2\\ A=3.14{\left(4\right)}^2\\ A=50.2sq.units\end{array}$

(b)

To determine

To Find: The circumference and area of circle.

Answer to Problem 10WE

  $C=12.5tunits$

  $A=12.56t^{2}sq.units$

Explanation of Solution

Given: $diameter=4t$ , use $\pi =3.14$

Given: $diameter=4t$

  $\begin{array}{l}r=\frac{d}{2}\\ r=\frac{4t}{2}\\ r=2t\end{array}$

Circumference of a circle

  $\begin{array}{l}C=2\pi r\\ C=2(3.14)\left(2t\right)\\ C=12.5tunits\end{array}$

Area of circle

  $\begin{array}{l}A=\pi r^2\\ A=3.14{\left(2t\right)}^2\\ A=12.56t^{2}sq.units\end{array}$