proving using calculus without trig identity

Please I really need help with this hw question

Prove without trig identity that f(x)=0 for

F(x)=Asin^2(Bx+C)+Acos^2(Bx+C)
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 Quote by kebabs Please I really need help with this hw question Prove without trig identity that f(x)=0 for F(x)=Asin^2(Bx+C)+Acos^2(Bx+C)
You're not supposed to use the obvious identity that simplifies this? I suppose you could just use the derivatives of sin and cos along with the chain rule to directly compute the derivative. But eventually you'll need to simplify using some trig identity.
 I can't use trig identy to solve it

proving using calculus without trig identity

I mean I'm not allowed to

Mentor
 Quote by kebabs Please I really need help with this hw question Prove without trig identity that f`(x)=0 for F(x)=Asin^2(Bx+C)+Acos^2(Bx+C)
What is F'(x) if $F(x)=A\sin^2(Bx+C)+A\cos^2(Bx+C)\,?$

Recognitions:
Homework Help
 Quote by SteveL27 You're not supposed to use the obvious identity that simplifies this? I suppose you could just use the derivatives of sin and cos along with the chain rule to directly compute the derivative. But eventually you'll need to simplify using some trig identity.
Are you sure? I was able to get F'(x) = 0 by using the chain rule, and yet I didn't use any trig identity.