How do you differentiate sin(x^2)(cos(x^2))sin(x2)(cos(x2))?

1 Answer
Sep 7, 2015

d/dx sin(x^2) cos(x^2) =2xcos(2x^2) ddxsin(x2)cos(x2)=2xcos(2x2)

Explanation:

This problem can also be solved by directly applying the differentiation rules:

d/dx sin(x^2) cos(x^2)ddxsin(x2)cos(x2)

First, use the product rule:
=sin(x^2) d/dx cos(x^2) + cos(x^2)d/dx sin(x^2) =sin(x2)ddxcos(x2)+cos(x2)ddxsin(x2)

Then, each derivative can be solved using the chain rule:
=-sin(x^2) sin(x^2) d/dx x^2 + cos(x^2)cos(x^2)d/dx x^2 =sin(x2)sin(x2)ddxx2+cos(x2)cos(x2)ddxx2

=-2xsin^2(x^2) + 2xcos^2(x^2) =2xsin2(x2)+2xcos2(x2)

At this point, we can simplify the expression by factoring out 2x2x and applying the double angle identity cos 2theta = cos^2 theta - sin^2 thetacos2θ=cos2θsin2θ :

=2x(cos^2(x^2)-sin^2(x^2)) =2x(cos2(x2)sin2(x2))

=2xcos(2x^2) =2xcos(2x2)