Basic Trig

This isn't my homework, it's a question

Hypotnous = H
Adjacent = Ha
Opposite =Ho


H = 15
Ho = 4
Ha = 6

What is the Theta? - How do I find the theta from the tiny number I get when I do the cosign\sin shit?

For added pleasure. How do I do reverse sin\cos\tangent- a.k.a Arc sin\cos\tan

THANKS TO YOU. Physics 2053

sin x = sum{ n=0->inf, (-1)^n [ x^(2n+1) ]/[ (2n+1)! ] }

x is in radians and the rest is arithmetic lol.