sin2x − cos2x − tan2x = 2sin2x − 2sin4x − 1/

Question

1 − sin2x
for x = 45

Answer 1

I can't quite make out your equation, but it is easy to plug in x=45

sin2x = sin90 = 1
sin4x = sin180 = 0

and so on.

If that still stumps you, show us how far you got, and try using some parentheses to make things clear, such as

1/(2-sin2x)

and say sin^2x or sin^2(x) if you mean sin squared of x instead of sin(2x)