# Math Help - Huge trouble with trig equations

1. ## Huge trouble with trig equations

Say we have 3sinx = -3 from -pi to pi, for example.

x = sin^-1(-1)

So it's negative in the bottom quadrants.

If I go 90 from tan, it ends up at 270, and 90 from cos ends up at 360.

The book has the answer as -pi/2, or -90. Is this expressing it in its original form as a negative or what? I'm just really confused. I can do the positive domains fine.

Cheers.

2. Why are you doing anything with cosine or tangent?

$\sin\left(-\frac{\pi}{2}\right) = -1$

What else is there to consider?

3. Oh well we have to solve for the domain using a unit circle.