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If sinθ= 4/5 in quadrant II, what is cosθ?

 Jul 20, 2020
 #1
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Q II has negative values of cosine

 

sin^2 + cos^2 = 1

(4/5 )^2 + cos^2 = 1

cos^2 = 9/25      cos   = +- 3/5     but we need negative in Q II   so   - 3/5

 Jul 20, 2020

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