Chapter 11, Problem 28CUR

To determine

To Find: Value of $EF$ to the nearest integer.

Answer to Problem 28CUR

13

Explanation of Solution

Given:

Right angled $\Delta DEF$ with $m\angle E=90°,m\angle F=42°$

  $DE=12$

Formula used:

  1. $\tan \theta =\frac{Perpendicular}{Base}$

Representing the given triangle as following:

  

Using formula for $\tan \theta$ :

  $\begin{array}{l}\tan F=\tan 42°=\frac{DE}{EF}=\frac{12}{EF}\\ \Rightarrow EF\approx 13\end{array}$