Question

In ADEF, the measure of ZF=90°, DE = 91 feet, and FD = 59 feet. Find the measure of D to the nearest degree.

Answer 1

m∠D = 50º

Step-by-step explanation

Triangle DEF is:

We want to know the measure of angle D, knowing the side lengths DE (the hypotenuse of the triangle) and FD (the adjacent side to angle D). We can use the cosine of D:

`\begin{gathered} \cos \angle D=(59)/(91) \\ \angle D=\cos ^(-1)(59)/(91) \\ \angle D=49.58º\approx50º \end{gathered}`