What are the formulas for COS, TAN, and SIN?

I'm guessing that you don't really want the formulas. I think what you actually want

is the definitions of those functions of an acute angle when it's in a right triangle.

Cosine = (adjacent side) / (hypotenuse)

Tangent = (opposite side) / (adjacent side)

Sine = (opposite side) / (hypotenuse)

Tell me if I'm wrong, and I'll find some formulas for you.