Question

Qual a derivada de sen²x?

Answer 1

regra da cadeia
$\boxed{\boxed{\left(u^{N}\right)' = N*u^{N-1}*u'}}$

$y= (sen(x))^2$
temos
U = sen(x)
U' = cos(x)

então 
$y= u^2\\\\y'=2u^{2-1}*u'\\\\y'=2*u*u'\\\ y'=2*sen(x)*cos(x)$

Answer 2

$\sf\dfrac{d}{dx}[sen^2(x)]=2sen(x)cos(x)=sen(2x)$