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calyne

show me how to calculate -sin(3pi/4)

  • 2 years ago
  • 2 years ago

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  1. Dockworker
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    you want to get the reference angle, that is the first quadrant angle that has the same value, maybe varying only by sign

    • 2 years ago
  2. Dockworker
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    we know the sign is positive in the 2nd quadrant and in the first quadrant

    • 2 years ago
  3. Dockworker
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    of sine, that is

    • 2 years ago
  4. Dockworker
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    so this question is the exact same thing as -sin(3pi/4-pi/2)

    • 2 years ago
  5. Dockworker
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    which is -sin(pi/4)

    • 2 years ago
  6. Dockworker
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    think of the unit circle with radius 1, what would the y-value need to be with respect to the radius for theta to be pi/4?

    • 2 years ago
  7. Mertsj
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    |dw:1333508390565:dw| So \[-\sin\frac{3\pi}{4}=-\sin\frac{\pi}{4}=-\frac{\sqrt{2}}{2}\]

    • 2 years ago
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