The following image shows my confusion:
I don't have any trouble doing the derivative, but how did they arrive from the second-last line to the last?
I know that sin^2(x) + cos^2(x) = 1, but I can't see how to relate that here.
The following image shows my confusion:
I don't have any trouble doing the derivative, but how did they arrive from the second-last line to the last?
I know that sin^2(x) + cos^2(x) = 1, but I can't see how to relate that here.