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Finding Quadrant and Sign of a Trigonometric Function

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Find the quadrant of the angle, sign, reference angle and value of the trigonometric functions below:

1. sin 642°

2. csc ( -8.785)

3. sec ( 23pi / 5 )

4. tan ( -7.228)

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https://brainmass.com/math/trigonometry/finding-quadrant-sign-trigonometric-function-194255

Solution Preview

(1) 642 degrees = IV quadrant, sin 642 deg is negative, the reference angle = 78 deg and sin 642 deg = -0.9781

(2) -8.785 ...

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