1. The problem is to simplify or understand the expression $\sin^2 x$. 2. The notation $\sin^2 x$ means $(\sin x)^2$, which is the square of the sine of $x$. 3. A useful identity involving $\sin^2 x$ is the Pythagorean identity: $$\sin^2 x + \cos^2 x = 1$$ 4. From this, you can express $\sin^2 x$ as: $$\sin^2 x = 1 - \cos^2 x$$ 5. This identity is often used to simplify expressions or solve equations involving trigonometric functions. 6. If you want to express $\sin^2 x$ in terms of a double angle, use the identity: $$\sin^2 x = \frac{1 - \cos(2x)}{2}$$ 7. This can be helpful in integration or solving trigonometric equations. Final answer: $\sin^2 x$ is the square of $\sin x$ and can be rewritten as $\frac{1 - \cos(2x)}{2}$ or $1 - \cos^2 x$ depending on the context.