How do you find the cotangent of an angle?

My problem is: Find the exact value of cot(-315degrees).

I don't know how to do this.

Any help would be great.

remember the cotangent is 1/tangent

so find tan(-315)
-315 is the same as 45º
so tan(-315) = tan 45 = 1 (from our 45,45 90 triangle)

so cot(-315) = 1/1 = 1