### Home > PC > Chapter 11 > Lesson 11.1.3 > Problem 11-46

11-46.

Multiply both sides by cos²(*θ* + *π*/4).

Note: Steps can be done in various orders.

Expand sin(*θ* + *π*/4) and cos(*θ* + *π*/4) using the angle sum identities.

Change sin(*π*/4) and cos(*π*/4) to their numeric values.

Multiply both sides by *r*.

Substitute *x* for *r* cos(*θ*), etc.

Simplify.