1. Finding angle measures using trigonometry
Chapter 9.1
Finding angle measures using trigonometry

2. Inverse Trigonometric Ratios
Recall that we used sine, cosine, and tangent to find missing side lengths in right triangles
We use inverse trig ratios to find missing angle measures:
sine-1, cos-1, tan-1,

3. Example 4
Find Angle Measures Using Inverse Trigonometric Ratios
Use a calculator to find the measure of P to the nearest tenth.

4. Example 4
B. Find the measure of angle B to the nearest tenth.

5. Example 4
B. Find the measure of angle A to the nearest tenth.

6. Example 4
Use a calculator to find the measure of D to the nearest tenth.
A. 44.1°
B. 48.3°
C. 55.4°
D. 57.2°

7. Find the angle of elevation or depression
A. A 27 foot tall oak tree casts a shadow 25 feet long. Find the angle of elevation of the sun.

8. Find the angle of elevation or depression
B. Nikki is 65 inches tall. At 2pm, she casts a shadow that is 25 inches long. Find the angle of elevation of the sun at 2pm.

9. Find the angle of elevation or depression
C. Rishi is on an airplane 10,000 feet above sea level. He sees a ship in the ocean 15,000 feet away from the airplane. Find the angle of depression.

10. Find the angle of elevation or depression
D. Faith lives in the penthouse suite of a 130 foot tall apartment building. From her window, Faith can see Jelisa walking her dog in the park 50 feet from the base of the building. Find the angle of depression.