1.  A trigonometric ratio is a ratio of the lengths of 2 sides of a right triangle.  You will learn to use trigonometric ratios of a right triangle to determine side length and angle measurement.

2.  Trigonometry is from the ancient Greek language and means “measurement of triangles”, and was first used in 1595.  The 3 basic ratios are sine, cosine and tangent. These are abbreviated as sin, cos, and tan respectively.

3.  The sine, cosine, and tangent of the acute angle A are defined as: › A Hypotenuse Side adjacent  A Side opposite  A

4. S = O/H C=A/H T=O/A

5.  Sketch a 30  -60  -90  triangle. Use “1” as the length of the shorter leg. Therefore the hypotenuse will be 2 and the longer leg will be 1  3. › 30  2 33 1 Note: Similar triangles always have the same trig ratios!!!!

6.  You are measuring the height of a tree. You stand 45 feet from the base of the tree. You measure the angle of elevation from a point on the ground to the top of the tree to be 59  (because you always carry around a clinometer, which allows you to do this). What trig ratio would use the known measures height and elevation? 59  45ft h

7. Sin M  0.5812 Cos M  0.8137 Tan M  0.7143 Sin T  0.8137 Cos T  0.5812 Tan T  1.4 Sin A  0.7071 Cos A  0.7071 Tan A = 1 Sin N  0.7071 Cos N  0.7071 Tan N = 1 Sin Q = 0.8 Cos Q = 0.6 Tan Q  1.3333 Sin R = 0.6 Cos R = 0.8 Tan R = 0.75

8.  Find the value of each variable. Round decimals to the nearest tenth. 1. 2. x  10.4, y  6.7x  1.7, y  4.7