SOLUTION: Is sin t equals -4/5 and tan t is negative, what is the value of cos t

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Question 1028356: Is sin t equals -4/5 and tan t is negative, what is the value of cos t

Answer by ikleyn(52817) About Me  (Show Source):
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Is sin t equals -4/5 and tan t is negative, what is the value of cos t
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Since sin(t) is negative and tan(t) is negative, the angle t is in fourth quarter.

Then cos(t) = sqrt%281-sin%5E2%28t%29%29 = sqrt%281-%28-4%2F5%29%5E2%29 = sqrt%281-16%2F25%29 = sqrt%289%2F25%29 = 3%2F5.