Question 1202751
csc^2y tan^2y - 1 = tan^2y


(1/sin^2y)(sin^2y)/cos^2y) -1

(1/cos^2y)-1


(1- cos^2y)/cos^2y          but  (sin^2y+cos^2=1)


= sin^2y/cos^2y

= tan^2y