Question

How do you find the derivative of `y=cos^2theta`?

Answer 1

`dy/(d theta)=-sin2theta`

Explanation:

`"differentiate using the "color(blue)"chain rule"`

`"given "y=f(g(x))" then"`

`dy/dx=f'(g(x))xxg'(x)larrcolor(blue)"chain rule"`

`y=cos^2theta=(costheta)^2`

`rArrdy/(d theta)=2costhetaxxd/(d theta)(costheta)`

`color(white)(xxxxx)=-2sinthetacostheta`

`color(white)(xxxxx)=-sin2theta`