1. Section 8.5 Tangent Ratio

2. What is Trigonometry ? The study of triangles and their measurements.

3. Three Trig. Ratios 1) Sine 2) Cosine 3) Tangent Why use this??????

4. What is the tangent ratio ? ABBREVIATED FORM

5. 1. Find tan X and write as a ratio. 2. Find tan Y and write as a ratio. opposite adjacent

6. On you calculator. On your calculator locate the sin, cos, and tan buttons. Then make sure your MODE is set to DEGREES. Use sin, cos, and tan when you KNOW THE ANGLE MEASUREMENT

7. On you calculator. Notice sin -1, cos -1, and tan -1 above the regular sin, cos, tan buttons. Those stand for inverse sin, inverse cos, and inverse tan. Use these buttons with the 2 nd button. Use them when you DON’T KNOW THE ANGLE.

8. Easy stuff – on you calculator. Find tangent of the following angles. 3) tan 46 o = 4) tan 78 o = 5) tan ? = 0.1944 6) tan ? = 6.3138 1.035530314 4.704630109 11.00108712 o 81.00006798 o

9. z 7) Find the measure of the missing angles and the missing length. 180 – 90 – 66.0375 = 23.9625

10. Find the missing angles. 8) 15 (it’s a triple!)15 180 – 90 – 28.0725 = 61.9275 =m ∠ B

11. Find the value of x. O

12. o A B C Find tan A, m ∠ B, tan B 10)

13. Road Grades 11) The grade of a road is the ratio of its rise to its run and is usually given as a percent. Find the angle that the road makes with the horizontal if its grade is 4.5%. Horizontal xoxo 4.5% 9 200

14. PRACTICE Page 306 – 307 Page 306 – 307 Classroom Exercises Classroom Exercises #1 - 9 #1 - 9