559 5.3 Trigonometric Function Values and Angle Measures CONCEPT PREVIEW Fill in the blanks to correctly complete each sentence. 7. The value of sin 240° is because 240° is in quadrant . (positive / negative) The reference angle is , and the exact value of sin 240° is . 8. The value of cos 390° is because 390° is in quadrant . (positive / negative) The reference angle is , and the exact value of cos 390° is . 9. The value of tan1-150°2 is because -150° is in quadrant . (positive / negative) The reference angle is , and the exact value of tan1-150°2 is . 10. The value of sec 135° is because 135° is in quadrant . (positive / negative) The reference angle is , and the exact value of sec 135° is . 5.3 Exercises CONCEPT PREVIEW Match each trigonometric function in Column I with its value in Column II. Choices may be used once, more than once, or not at all. I 1. sin 30° 2. cos 45° 3. tan 45° 4. sec 60° 5. csc 60° 6. cot 30° II A. 23 B. 1 C. 1 2 D. 23 2 E. 223 3 F. 23 3 G. 2 H. 22 2 I. 22 Suppose ABC is a right triangle with sides of lengths a, b, and c and right angle at C. A C c b B a Use the Pythagorean theorem to find the unknown side length. Then find exact values of the six trigonometric functions for angle B. Rationalize denominators when applicable. See Example 1. 15. a = 5, b = 12 16. a = 3, b = 4 17. a = 6, c = 7 18. b = 7, c = 12 19. a = 3, c = 10 20. b = 8, c = 11 21. a = 1, c = 2 22. a = 22, c = 2 Find exact values or expressions for sin A, cos A, and tan A. See Example 1. 12. 45 A 53 28 13. A n m p 14. A z y k 11. 29 A 20 21
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