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radh

  • 3 years ago

Find each exact value if 0 < x < pi/2 and 0 < y < pi/2 .

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  1. radh
    • 3 years ago
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    1. cos (x + y) if sin x = 5/13 and sin y = 4/5 2. sin (x – y) if cos x = 8/17 and cos y = 3/5 3. tan (x – y) if csc x = 13/5 and cot y = 4/3

  2. waterineyes
    • 3 years ago
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    In first case, you are to find cosx and cosy..

  3. waterineyes
    • 3 years ago
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    Using the identity : \[\cos^2(x) + \sin^2(x) = 1\]

  4. waterineyes
    • 3 years ago
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    Then after finding you are supposed to use : \[\cos(x+y) = \cos(x) \cos(y) - \sin(x) \sin(y)\]

  5. radh
    • 3 years ago
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    Thanks for the method. I wasn't sure what I was supposed to use here.

  6. waterineyes
    • 3 years ago
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    Must remember for the intervals you are given with.. x and y are in 0 to 90 interval, and all trigonometric ratios in this range will be positive..

  7. waterineyes
    • 3 years ago
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    Just try once...

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