how does tan work

It is also a process called melanogenesis, where melanin is produced by melanocytes when exposed to UV radiation.

Tangent is the opposite side over the adjacent side.

Tan(B) in a triangle ABC (where side 'c' is the hypotenuse) would be b/a

For instance, in a triangle with side lengths 3-4-5 (coinciding to 'a', 'b', and 'c' respectively) tan(B) would be 4/3, because the side opposite angle 'B' is 4, and the side adjacent to angle 'B' is 3.