tan(45) = 1 ---> tan2(45) = 1
cos(60) = 1/2 ---> cos2(60) = 1/4
sin(45) = sqrt(2) / 2
cos(45) = sqrt(2) / 2
tan(60) = sqrt(3)
tan2(45) - cos2(60) = x · sqrt(2) / 2 · sqrt(2) / 2 · sqrt(3)
1 - 1/4 = x · 2 · sqrt(3) / 4
3/4 = (1/2) · sqrt(3) · x
1/2 · sqrt(3) = x