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aussy123

  • 3 years ago

Given: a and B are first-quadrant angles, sin a=5/13, and cosB= 3/5. evaluate sin(a-B). a.) -33/65 b.) 33/65 c.) 63/65

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  1. ash2326
    • 3 years ago
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    Use this here \[\sin (A-B)=\sin A\times \cos B-\sin B\times \cos A\]

  2. ash2326
    • 3 years ago
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    sin a=5/13, and cosB= 3/5

  3. aussy123
    • 3 years ago
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    I tried this but the book is asking me to subtitute pi/2 for a

  4. aussy123
    • 3 years ago
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    and I know I have to solve for sin B and cos A

  5. ash2326
    • 3 years ago
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    \[\sin (B)=\cos (\frac {\pi}{2} -B)\] \[\cos A=\sin (\frac{\pi}{2}-{A})\] you can use \[\sin^2 x+\cos^2 x=1\] to figure out sin B and cos A

  6. aussy123
    • 3 years ago
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    ok ill try this

  7. aussy123
    • 3 years ago
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    cos a= 12/13

  8. ash2326
    • 3 years ago
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    correct :)

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