I know this is kind of dumb but cos(-x) = - cos (x) ? Right?
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Originally Posted by sakonpure6 I know this is kind of dumb but cos(-x) = - cos (x) ? Right? NO! It is not correct. $\displaystyle \cos(x)$ is an even function, therefore $\displaystyle \cos(x)=\cos(-x)~.$
Omg thank you!!! I knew that sin(-x) = - sin x but when I put in a negative value for cos say, cos (-60) i got a positive number. Thanks!!!!
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