SOLUTION: Given that sinx = 3/5 and cosy = 7/25, with x and y both being Quadrant I angles, find cosx AND siny

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Question 1036014: Given that sinx = 3/5 and cosy = 7/25, with x and y both being Quadrant I angles, find cosx AND siny
Answer by ikleyn(52794) About Me  (Show Source):
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Given that sinx = 3/5 and cosy = 7/25, with x and y both being Quadrant I angles, find cosx AND siny
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cos(x) = sqrt%281-sin%5E2%28x%29%29 = sqrt%281+-+%283%2F5%29%5E2%29 = sqrt%281+-+9%2F25%29 = sqrt%28%2825-9%29%2F25%29 = sqrt%2816%2F25%29 = 4%2F5.


The sign  "+"  was chosen at the square root because the cosine is positive in the first quadrant.


Similarly,  sin(y) = sqrt%281-cos%5E2%28y%29%29 = sqrt%281-%287%2F25%29%5E2%29 = sqrt%28%28625-49%29%2F625%29 = sqrt%28576%2F625%29 = 24%2F25.

The sign  "+"  was chosen at the square root because the sine is positive in the first quadrant.