Pre-Calculus COS question

JasonMC

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Oct 16, 2011
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I'm having difficulty with this one problem:

COS(-3pi/4)

Its the negative. I don't understand how to evaluate it properly.

Thanks!!
 
cos(-x) = cos(x). Careful though, sin(-x) = -sin(x). From here you should be able to work out how every trigonometric function handles negatives...
 
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