1. Trig Ratios C 5 2 A M 4. If C = 20º, then cos C is equal to:
Be sure to discuss if C = 20, then sin C would equal ?
4. If C = 20º, then cos C is equal to:
A. sin 70 B. cos 70 C. tan 70

2. Homework Review

3. CCGPS Geometry Day 17 (8-29-13)
UNIT QUESTION: What patterns can I find in right triangles?
Standard: MCC9-12.G.SRT.6-8
Today’s Question:
How do we use trig ratios to find the missing sides and angles of a triangle?

4. hypotenuse
hypotenuse
opposite
opposite
adjacent
adjacent

5. Finding an angle. (Figuring out which ratio to use and getting to use an inverse trig button.)

6. Ex: 1. Figure out which ratio to use. Find x
Ex: 1 Figure out which ratio to use. Find x. Round to the nearest tenth.
20 m
40 m
Shrink yourself down and stand where the angle is.
Tan-1
20 / 40 )
Now, figure out which trig ratio you have and set up the problem.

7. Ex: 1. Figure out which ratio to use. Find x
Ex: 1 Figure out which ratio to use. Find x. Round to the nearest tenth.
15 m
50 m
Shrink yourself down and stand where the angle is.
Sin-1
15 / 50 )
Now, figure out which trig ratio you have and set up the problem.

8. Ex. 3: Find . Round to the nearest degree.
17.2 9

9. Ex. 4: Find . Round to the nearest degree.7 23

10. Ex. 5: Find . Round to the nearest degree.
200
400

11. Finding a side. (Figuring out which ratio to use and getting to use a trig button.)

12. Ex: 1. Figure out which ratio to use. Find x
Ex: 1 Figure out which ratio to use. Find x. Round to the nearest tenth.
20 m x
Shrink yourself down and stand where the angle is.
tan 20 55 )
Now, figure out which trig ratio you have and set up the problem.

13. Ex: 2 Find the missing side. Round to the nearest tenth.
80 ft x
tan 80  ( 72 ) ) =
Shrink yourself down and stand where the angle is.
Now, figure out which trig ratio you have and set up the problem.

14. Ex: 3 Find the missing side. Round to the nearest tenth.
Shrink yourself down and stand where the angle is.
Now, figure out which trig ratio you have and set up the problem.

15. Ex: 4 Find the missing side. Round to the nearest tenth.
20 ft x

16. When we are trying to find a side we use sin, cos, or tan.
When we are trying to find an angle we use (INVERSE) sin-1, cos-1, or tan-1.

17. Classwork
Missing Sides WS

18. Missing Sides and Angles WS
Homework
Missing Sides and Angles WS