Find the derivative of \( \sin^2 x \):
\[
\frac{d}{dx} \left( \sin^2 x \right)
\]
Show Hint
To differentiate functions like \( \sin^2 x \), use the chain rule: \( \frac{d}{dx} \left( f(g(x)) \right) = f'(g(x)) \cdot g'(x) \). For \( \sin^2 x \), apply this to \( f(u) = u^2 \) and \( g(x) = \sin x \).
We need to differentiate \( \sin^2 x \) with respect to \( x \). Using the chain rule:
\[
\frac{d}{dx} \left( \sin^2 x \right) = 2 \sin x \cdot \cos x
\]
This simplifies to:
\[
2 \cos x \sin x
\]
which is the correct result. Therefore, the correct option is:
\[
\boxed{2 \cos x}
\]