 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.

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

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

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

 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!!!!

 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

Sin M  Cos M  Tan M  Sin T  Cos T  Tan T  1.4 Sin A  Cos A  Tan A = 1 Sin N  Cos N  Tan N = 1 Sin Q = 0.8 Cos Q = 0.6 Tan Q  Sin R = 0.6 Cos R = 0.8 Tan R = 0.75

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