how do i get left hand side to equal right hand side??

((Cot^2B)/(Cos^2B))-Cot^2B=1

LS = (cos^2 B / sin^2 B)/cos^2 B - cos^2 B/sin^2 B

= cos^2 B/(sin^2 B cos^2 B) - cos^4 B/(sin^2 B cos^2 B)
= cos^2 B(1 - cos^2 B)/(sin^2 B cos^2 B)
= cos^2 B sin^2 B/(sin^2 B cos^2 B)
= 1
= RS