1. Trigonometric Ratios Trigonometry – The branch of mathematics that deals with the relations between the sides and angles of triangles, and the calculations based on them. - Webster’s Collegiate Dictionary Trigonometric Ratio – A ratio of the lengths of sides of a right triangle.

2. Trigonometric Ratios Sine  A = length of the side opposite the angle length of the hypotenuse Cosine  A = length of the side adjacent to the angle length of the hypotenuse Tangent  A = length of the side opposite the angle length of the side adjacent to the angle S-O-H-C-A-H-T-O-A

3. Example 4-1f Find sin A, cos A, tan A, sin B, cos B, and tan B. Express each ratio as a fraction and as a decimal.

4. Example 4-1g Answer:

5. a. Use a calculator to find sin 48° to the nearest ten thousandth. b. Use a calculator to find cos 85° to the nearest ten thousandth. Example 4-2c Answer:

6. Example 4-3c CONSTRUCTION The bottom of a handicap ramp is 15 feet from the entrance of a building. If the angle of the ramp is about how high does the ramp rise off the ground to the nearest inch? Answer: about 15 in.