You can put this solution on YOUR website! sin^2x(1+cot^2x)=1
distributing the sin^2x:
sin^2x + sin^2xcot^2x = 1
substitute identity of "cot^2x" = cos^2x/sin^2x:
sin^2x + sin^2x(cos^2x/sin^2x) = 1
sin^2x + cos^2x = 1
substitute left side with identity of "sin^2x + cos^2x" = 1:
1 = 1