2 cos (t)
d / 2 \ --\cos (t)/ dt
Let u=cos(t)u = \cos{\left(t \right)}u=cos(t).
Apply the power rule: u2u^{2}u2 goes to 2u2 u2u
Then, apply the chain rule. Multiply by ddtcos(t)\frac{d}{d t} \cos{\left(t \right)}dtdcos(t):
The derivative of cosine is negative sine:
The result of the chain rule is:
Now simplify:
The answer is:
-2*cos(t)*sin(t)
/ 2 2 \ 2*\sin (t) - cos (t)/
8*cos(t)*sin(t)