problem: 1/(4-x^2)

(ill be using o to represent theta)

x=sino

dx=2coso do

sin=x/2

integrate 1/2coso * 2coso do = integrate do

Looking at the triangle I draw I can tell that i screwed up somewhere but the form a-x is sin

the answer I end up with is arcsin(x/2) but I know it should be arctan(x/2) i just cant make it work.