### Home > CALC > Chapter 10 > Lesson 10.1.2 > Problem10-15

10-15.

Use the trigonometric identity $\operatorname{cos}(2θ) = 2\operatorname{cos}^2 θ − 1$ to rewrite the expressions below.

1. $\operatorname{sin}^2 x$

$2\cos^2(x)=\cos(2x)+1$

2. $\operatorname{cos}^2 x$

$\cos^2(x)=1-\sin^2(x)$

$\cos(2x)=2(1-\sin^2(x))-1$
Now solve for $\operatorname{sin}^2(x)$.