# Trigonometric Equations

sinx + cosx = 0

N/A

## The Attempt at a Solution

sinx + cosx = 0

sinx = -cosx
sinx = (+/-) sqrt(sin^2x - 1)
(sinx)^2 = (+/-) sqrt(sin^2x - 1)^2
sinx = sin^2x - 1

Not really too sure what to do from here on.

The answer is 3$$\pi$$/4 and 7$$\pi$$/4.

I appreciate the help, thanks in advance.

$$sin x = -\cos x$$

Divide by cosx, what identity do you get?

HallsofIvy