LHS = 1- (1- cos²T) 
                     tan²t

        = 1-     (sin ² T)               ------->>> 1-cos²T = sin²T  &   tan ²T = sin²T/cos²T
                    sin²T/cos²T

        = 1-cos ²T

        = sin ² T------->>> 1-cos²T = sin²T

Therefore, RHS suppose to be----->>  sin ² T  !!  ?????  

Did I get it right !  WOW !  I better participate on the TV show " Are You Smarter Than a 5th Grader?". LOL ! :D :D :p