/ / 2\\ log\cos\x //
d / / / 2\\\ --\log\cos\x /// dx
Let .
The derivative of is .
Then, apply the chain rule. Multiply by :
Let .
The derivative of cosine is negative sine:
Then, apply the chain rule. Multiply by :
Apply the power rule: goes to
The result of the chain rule is:
The result of the chain rule is:
Now simplify:
The answer is:
/ 2\ -2*x*sin\x / ------------ / 2\ cos\x /
/ / 2\ 2 2/ 2\\ | 2 sin\x / 2*x *sin \x /| -2*|2*x + ------- + -------------| | / 2\ 2/ 2\ | \ cos\x / cos \x / /
/ 2/ 2\ 2 / 2\ 2 3/ 2\\ | 3*sin \x / 4*x *sin\x / 4*x *sin \x /| -4*x*|3 + ---------- + ------------ + -------------| | 2/ 2\ / 2\ 3/ 2\ | \ cos \x / cos\x / cos \x / /