### Home > PC > Chapter 9 > Lesson 9.3.4 > Problem 9-147

9-147.

Solve: sin^{4} *x* − cos^{4} *x* =

Factor.

Simplify using identity.

Substitute:

sin^{2}*x* = 1 − cos^{2}*x*

Simplify.

Divide both sides by −2.

Square root both sides.

Solve for *x*.

9-147.

Solve: sin^{4} *x* − cos^{4} *x* =

Factor.

Simplify using identity.

Substitute:

sin^{2}*x* = 1 − cos^{2}*x*

Simplify.

Divide both sides by −2.

Square root both sides.

Solve for *x*.