- #1

Rectifier

Gold Member

- 313

- 4

**The problem**

I want to solve ##tan(a)=-1## where a is in degrees.

**The attempt**

## tan(a)= \frac{sin(a)}{cos(a)}=-1 \ \ cos(a) \neq 0 \\ \frac{sin(a)}{cos(a)}=-1 \\ sin(a)=-cos(a) \\ -sin(a)=cos(a) \\ sin(-a)=cos(a) ##

I have no idea how to continue from here.