Question

find ( mangle d ).
write your answer as an integer or as a decimal rounded to the nearest tenth.
( mangle d=) 。

Explanation:

Step1: Recall the cosine formula

In a right - triangle \( \cos D=\frac{\text{adjacent}}{\text{hypotenuse}} \). Here, the adjacent side to angle \( D \) is \( FD = 7 \), and the hypotenuse \( ED=10 \). So, \( \cos D=\frac{7}{10}=0.7 \).

Step2: Find the angle using the inverse cosine function

We know that \( D=\cos^{-1}(0.7) \). Using a calculator, \( \cos^{-1}(0.7)\approx45.6^{\circ} \).

Answer:

\( 45.6 \)