1. Trig Functions of Acute Angles
Lesson 2.2

2. Right Triangle Ratios Given a right triangle Ratios A c b B C a
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3. Right Triangle Ratios Given a specific triangle determine the ratios
How to find the hypotenuse?
Use the Pythagorean theorem
Ratios 7 5 B

4. Right Triangle Ratios
Note: Text suggests importance of memorizing table on pg …
Consider instead memorizing some standard triangles and deriving table as needed

5. Right Triangle Ratios
Some important relationships for standard triangles
30°
45° 2 2 1
45°
60° 1 1
60° 1

6. Reciprocal Trig Functions
Secant
Cosecant
Cotangent
Note: newer models of calculators will have these built in
Older systems can create functions
Older TI-89's may be updated

7. Evaluating Trig Expressions
Use calculator
Important to keep track of when calculator is in radian or degree mode
Use 2nd D to have function evaluate with degrees, even when in radian mode

8. Exercises for 2.2A
Page 142
1 – 49 EOO

9. Solving Triangles For now problem will involve right triangles
Usually one side and one angle will be given
Must find one or both of the other sides
Distance across the water?
Ask which trig ratio?
Write equation
Solve for unknown quantity
52°
31 m

10. Solving Triangles Some problems talk about angle of elevation
The line of sight above the horizontal
The angle of depression
The line of sight below the horizontal

11. Solving Triangles
Ask which trig ratio?
Write equation
Solve for unknown quantity
Find the height of an object by measuring distances and the angle of elevation
The angle of elevation is 37.5°
76.89 ft
Experiment with Elevation Spreadsheet

12. Exercises for 2.2B
Page 143
Exercises 53, 54, 57, 60, 63, 65,