Verifying Trigonometric Identities and Using Trigonometric Identities to Simplify Trigonometric Expressions · Exercise 40

Determine whether the identity is true or false. If false, find an appropriate equivalent expression.

$\frac{co{s}^2\theta -si{n}^2\theta }{1-ta{n}^2\theta }=si{n}^2\theta$

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Algebra and Trigonometry 2e · §9.1 Verifying Trigonometric Identities and Using Trigonometric Identities to Simplify Trigonometric Expressions · Exercise 40