Thread: how do you choose which half angle formula (tan) to use?

Mathwords: Half Angle Identities

for tangent u/2, it shows two formulas.

how do you know which one to use? or do they equal the same thing

1-cos u / sin u

or

sin u / 1 + cos u

Originally Posted by algebra2

Mathwords: Half Angle Identities

for tangent u/2, it shows two formulas.

how do you know which one to use? or do they equal the same thing

1-cos u / sin u

or

sin u / 1 + cos u

They are all the same. (Note that all of them carry the +/- symbol on them. The page wasn't too clear about that.) Which you pick is determined by which is the most useful to you.

-Dan