Question

In ADEF, sin D = 3. What is cos E?390 15OA. 3915OB. 36O C. 99O D. 35039

Answer 1

SOLUTION

Given the question in the image, the following are the solution steps to answer the question.

STEP 1: Write the given ratio

$\begin{gathered} \sin D=\frac{36}{39} \\ This\text{ shows that:} \\ sin\theta=\frac{opp}{hyp} \\ opp=36,hyp=39 \end{gathered}$

STEP 2: Write the ratio for CAH

$\begin{gathered} \cos\theta=\frac{adj}{hyp} \\ hyp=39,adj=? \end{gathered}$

We solve for adjacent using pythagoras theorem

$\begin{gathered} adj^2=39^2-36^2 \\ adj=\sqrt{225}=15 \end{gathered}$

Therefore, the value of cos E will be given as:

$CosE=\frac{adj}{hyp}=\frac{36}{39}$

Answer is 36/39