1. INTRODUCTION TO TRIGONOMETRY “TRIANGLE MEASURES” Section 8.2 Objective: To find the length of a side of a right triangle, given one side and one acute angle.

2. MAKE A GUESS…. 55° 10 y Now make a conjecture about the value of y in the figure. Trigonometry will help us find the length of a side of a right triangle when we are given only one side and one acute angle. RECALL… 60° 10 x Find the value of x.

3. Evaluate each function on a calculator. a. sin 30° What do these numbers mean? Where do they come from? 0.5 0.87 0.58 b. cos 30 ° c. tan 30 °

4. TRIG DEFINITIONS sin (angle) = tan (angle) = cos (angle) = 30  5 10

5. TRIG DEFINITIONS sin (angle) = tan (angle) = cos (angle) = 30  3 6

6. So when I type sin 30  into my calculator, it is telling me that the RATIO of the leg opposite the 30  angle and the hypotenuse is or 0.5. So how am I going to remember this?

7. SohCahToa PPOSITEPPOSITE PPOSITEPPOSITE YPOTENUSEYPOTENUSE YPOTENUSEYPOTENUSE DJACENTDJACENT DJACENTDJACENT INEINE OSINEOSINE ANGENTANGENT Aaaahh!

8. Handbook page 18

9. Here’s what you need to be able to do: 1.Given the right triangle shown, state the ratio for the sine, cosine and tangent of  A and  B. A B 10 6

10. 2. Find the value of x in each triangle. a. b. 37° 18 x 43° x 4.1

11. 55° 10 y Now use trigonometry to find the actual value of y, rounded to the nearest hundredth.

12. Assignment WS: Intro to Trig Ratios: 1-19