1. Section 9.5: Trigonometric Ratios

2. trigonometric ratio – a ratio of the lengths of two sides of a right triangle. The three basic trigonometric ratios are sine, cosine, and tangent.

3. B hypotenuse c side opp. a A A C b side adjacent to A

4. Trigonometric Ratios sin A = side opposite A = a hypotenuse c cos A = side adjacent A = b hypotenuse c tan A = side opposite A = a side adjacent A b

5. Example 1: Use a calculator to approximate the given value to four decimal places. a)cos 13° ≈ 0.9744 b)sin 27° ≈ 0.4540 c)tan 66° ≈ 2.2460

6. Example 2: Find the sine, cosine, and tangent of angle D. E 14 50 F 48 D

7. Example 3: Find the value of each variable. Round decimals to the nearest tenth. t 34 23° s

8. HOMEWORK (Day 1) pg. 562 – 563; 10 – 32 even

9. angle of elevation – the angle that your line of sight makes with a line drawn horizontally.

10. Example 4: You are measuring the height of a building. You stand 100 feet from the base of the building. You measure the angle of elevation from a point on the ground to the top of the building to be 48°. Estimate the height of the building. About 111 ft

11. Example 5: A driveway rises 12 feet over a distance d at an angle of 3.5°. Estimate the length of the driveway. About 197 ft

12. HOMEWORK (Day 2) pg. 563; 34 – 39