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Chapter 4 Trigonometric Functions

Chapter 4 Trigonometric Functions

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<strong>Trigonometric</strong> <strong>Functions</strong><br />

46. − 250°+ 360°= 110°<br />

Because the angle is in quadrant II, the reference<br />

angle is θ′ = 180°− 110°= 70°.<br />

47. − 335°+ 360°= 25°<br />

Because the angle is in quadrant I, the reference<br />

angle is θ′ = 25°.<br />

48. − 359°+ 360°= 1°<br />

Because the angle is in quadrant I, the reference<br />

angle is θ′ = 1°.<br />

57.<br />

58.<br />

11 11 16 5<br />

− π + 4π<br />

= − π + π =<br />

π<br />

4 4 4 4<br />

Because the angle is in quadrant III, the reference<br />

5π<br />

π<br />

angle is θ′ = − π = .<br />

4 4<br />

17 17 24 7<br />

− π + 4π<br />

=− π + π =<br />

π<br />

6 6 6 6<br />

Because the angle is in quadrant III, the reference<br />

7π<br />

π<br />

angle is θ′ = − π = .<br />

6 6<br />

49. Because 4.7 lies between π ≈ 3.14 and 3 π ≈ 4.71 , it<br />

2<br />

is in quadrant III. The reference angle is<br />

θ′ = 4.7 −π<br />

≈ 1.56 .<br />

50. Because 5.5 lies between 3 π ≈ 4.71 and 2π ≈ 6.28 ,<br />

2<br />

it is in quadrant IV. The reference angle is<br />

θ′ = 2π<br />

−5.5 ≈ 0.78 .<br />

51. 565°− 360°= 205°<br />

Because the angle is in quadrant III, the reference<br />

angle is θ ′ = 205°− 180°= 25°.<br />

52. 553°− 360°= 193°<br />

Because the angle is in quadrant III, the reference<br />

angle is θ′ = 193°− 180°= 13°.<br />

53.<br />

54.<br />

55.<br />

56.<br />

17 π 17 12 5<br />

− 2π<br />

= π − π =<br />

π<br />

6 6 6 6<br />

Because the angle is in quadrant II, the reference<br />

5π<br />

π<br />

angle is θ′ = π − = .<br />

6 6<br />

11 π 11 8 3<br />

− 2π<br />

= π − π =<br />

π<br />

4 4 4 4<br />

Because the angle is in quadrant II, the reference<br />

3π<br />

π<br />

angle is θ′ = π − = .<br />

4 4<br />

23 π 23 16 7<br />

− 4π<br />

= π − π =<br />

π<br />

4 4 4 4<br />

Because the angle is in quadrant IV, the reference<br />

7π<br />

π<br />

angle is θ′ = 2π<br />

− = .<br />

4 4<br />

17 π 17 12 5<br />

− 4π<br />

= π − π =<br />

π<br />

3 3 3 3<br />

Because the angle is in quadrant IV, the reference<br />

5π<br />

π<br />

angle is θ′ = 2π<br />

− = .<br />

3 3<br />

59.<br />

60.<br />

25 25 36 11<br />

− π + 6π<br />

=− π + π =<br />

π<br />

6 6 6 6<br />

Because the angle is in quadrant IV, the reference<br />

11π<br />

π<br />

angle is θ′ = 2π<br />

− = .<br />

6 6<br />

13 13 18 5<br />

− π + 6π<br />

= − π + π =<br />

π<br />

3 3 3 3<br />

Because the angle is in quadrant IV, the reference<br />

5π<br />

π<br />

angle is θ′ = 2π<br />

− = .<br />

3 3<br />

61. 225° lies in quadrant III. The reference angle is<br />

θ ′ = 225°− 180°= 45°.<br />

2<br />

cos 45°=<br />

2<br />

Because the cosine is negative in quadrant III,<br />

2<br />

cos 225 ° = − cos 45 ° = − .<br />

2<br />

62. 300° lies in quadrant IV. The reference angle is<br />

θ ′ = 360°− 300°= 60°<br />

.<br />

3<br />

sin 60°=<br />

2<br />

Because the sine is negative in quadrant IV,<br />

3<br />

sin 300°=− sin 60°=− .<br />

2<br />

63. 210° lies in quadrant III. The reference angle is<br />

210 180 30<br />

θ ′ = °− °= °.<br />

3<br />

tan 30°=<br />

3<br />

Because the tangent is positive in quadrant III,<br />

3<br />

tan 210 ° = tan 30°= .<br />

3<br />

526<br />

Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall.

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