<PRE><B>Question 853612</B>
Let A be an angle in quadrant 3 with cos A= -(12/13). Let B be an angle in quadrant 1 with sin B=(2/7). Find the exact value of sin(A-B). Your answer should involve a square-root.
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cos(A) = -12/13
sin(A) = sqrt(13^2-12^2)/13 = 5/13
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sin(B) = 2/7
cos(B) = sqrt(7^2-2^2)/7 = sqrt(45)/7
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Ans: sin(A-B) = sin(A)cos(B) - cos(A)sin(B)
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= (5/13)(sqrt(45)/7) - (-12/13)(2/7)
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etc.
Cheers,
Stan H.
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