OpenStudy (anonymous):

how do i find the second derivative of cos^2x-sin^2x

6 years ago
OpenStudy (anonymous):

sorry i mean what is the derivative of this

6 years ago
OpenStudy (anonymous):

take the derivative one by one. (cos^2x)'=2cosx*(-sinx)=-2sinxcosx (-sin^2x)'=-2sinx*(cosx)=-2sinxcosx (cos^2x-sin^2x)'=-2sinxcosx-2sinxcosx=-4sinxcosx=-2sin2x

6 years ago
OpenStudy (anonymous):

thanks alot

6 years ago
OpenStudy (jamesj):

Alternatively, remember that cos(2x) = cos^2 x - sin^2 x Hence you can differentiate cos(2x) to get -2 sin(2x).

6 years ago