Trigonometry (I guess)
ΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣ
Also correction, Sigma's symbol is Σ, I made the symbol wrong.
ΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣΣ
Remember :
Sin = O/H
Cos = A/H
Tan = O/A
O is opposite of the right angle and the opposite of the angle given
A is the bottom, Or the line from "O" to the angle given
H is the slope that completes A to make the angle given