simplify. 1+tan^2(pi/2-x)

Using the identity   1 + tan²(θ )  = sec² (θ ), we have

1+tan^2(pi/2-x) = sec² (pi/2 - x ) = 1 / cos² (pi/2 - x) 

And since  cos(pi/2 -x) = sin(x)   we have

1/ (sin² (x) = csc²(x)

Csc^2(x)