1. Solving For Angles & Real World Data4
Solving For Angles & Real World Data

2. Standard 4.2
I can use trig functions to solve a triangle.

3. Solving for a missing angle
When you solve for a missing angle you must “UNDO” your trig function.
To do this we will use the inverse keys on your calculator.
Sin-1 Cos-1 Tan-1
Use addition and subtraction, multiplication and division, square root and squaring as inverse operations.

4. Ex. 1: Find . Round to four decimal places.9
17.2
2nd
tan
17.2 9 )
Shrink yourself down and stand where the angle is.
Now, figure out which trig ratio you have and set up the problem.
Make sure you are in degree mode (not radians).

5. Ex. 2: Find . Round to three decimal places.7
2nd
cos 7 23 ) 23
Make sure you are in degree mode (not radians).

6. Ex. 3: Find . Round to three decimal places.
200
400
2nd
sin
200
400 )
Make sure you are in degree mode (not radians).

7. When we are trying to find a side we use sin, cos, or tan.
When we are trying to find an angle
we use sin-1, cos-1, or tan-1.

8. Standard 4.3
I can use trig ratios to solve a real world problem.

9. Example 2
Find the angle a telephone pole wire makes with the ground when a 14.8-meter tall telephone pole casts a 18-meter long shadow.

10. Example 3
An ant is looking up at you with an angle of elevation of 24°. You are 5 feet tall. How far is the ant from your foot?

11. Example 4
A ladder leaning against a building makes an angle of 78 degrees with the ground. The foot of the ladder is 5 feet from the building. How long is the ladder?