SOLUTION: If sinA=-3/5 with A in Q3 find cosA/2

Question 1033520: If sinA=-3/5 with A in Q3 find cosA/2
Answer by ikleyn(52835) (Show Source): You can put this solution on YOUR website!
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If sinA=-3/5 with A in Q3 find cosA/2
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First find  cos(A) = - = - = - = - = - = .


   The sign is "-" before the square root, since A is in Q3.


Now,   = -    (see the lesson Trigonometric functions of half argument in this site)


=  =  =  = .


   The sign is "-" because  is in Q2 and cosine is negative in Q2.

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