1. Finding an angle. (Figuring out which ratio to use and getting to use the 2 nd button and one of the trig buttons. These are the inverse functions.) 5.4 Inverse Sine, Cosine and Tangent

2. Ex. 1: Find . Round to four decimal places. 9 17.2 Make sure you are in degree mode (not radians). 2 nd tan 17.29)

3. Ex. 2: Find . Round to three decimal places. 23 7 Make sure you are in degree mode (not radians). 2 nd cos 723)

4. Ex. 3: Find . Round to three decimal places. 400 200 Make sure you are in degree mode (not radians). 2 nd sin 200400)

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

6. Solve the right triangle. Round decimal answers to the nearest tenth. “To solve a right triangle” means to find the measures of all of its sides and angles.

7. ANSWER The angle measures are 42 o, 48 o, and 90 o. The side lengths are 70 feet, about 63 feet, and about 94 feet.

8. THEATER DESIGN Suppose your school is building a raked stage. The stage will be 30 feet long from front to back, with a total rise of 2 feet. A rake (angle of elevation) of 5 o or less is generally preferred for the safety and comfort of the actors. Is the raked stage you are building within the range suggested? ANSWER The rake is about 3.8 o, so it is within the suggested range of 5 o or less.

9. Solve a right triangle that has a 40 o angle and a 20 inch hypotenuse. ANSWER 40 o, 50 o, and 90 o, about 12.9 in., about 15.3 in. and 20 in.