it didnt, No offense, 1/x = x^ -1 are both inversesx • x^-1 =1 and x • 1/x =1 (in ANY MATH a multiplicative inverse, is a number that gives you the Identity when you multiply it. in Multiplication the Identitity is 1.) So, for x,y,z, anything, stuff....stuff × 1= stuffstuff × 1/stuff = 1stuff × stuff^-1 therefore 1/stuff = stuff^-1I KNOW THAT, just not sure why we have cotan and arctan if they do the same thing.