Sine, cosine, and tangent are trigonometric functions that relate to the edge lengths of the triangle.  Let the length of the hypotenuse, adjacent, and opposite sides be HYP, ADJ, and OPP respectively. 



Some people use the mnemonic SOH CAH TOA – meaning sine is opposite over hypotenuse, cosine is adjacent over hypotenuse, tangent is opposite over adjacent.

Example:
Consider the following triangle:

To determine θ, simply apply the inverse trigonometric function:


In code, you might write

• theta = atan(opp / adj);   or  theta = atan2(opp, adj);
• Note: these functions return the angle in radians.  To convert to degrees, simply multiply by (180.0f / M_PI).  Atan returns an angle defined on a 180 degree domain (-pi/2, pi/2], atan2 returns an angle defined on a 360 degree domain (-pi, pi].

High