Thread: Finding a derivative

If y = cosx^2 - sinx^2, then what does y' equal?

The answer is -2sin(2x), but how do you actually get this answer? I used the power and chain rules when solving it, but the answer I got isn't the same. Thanks.

Originally Posted by pocketasian

If y = cosx^2 - sinx^2, then what does y' equal?

The answer is -2sin(2x), but how do you actually get this answer? I used the power and chain rules when solving it, but the answer I got isn't the same. Thanks.

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Oh, that's right, that's an identity. Thank you very much!