Question

Verify The Identity
1. (1 + tan2u)(1 - sin2u) = 1
2.cot2x + csc2x = 2csc2x - 1
3.1 + sec2xsin2x = sec2x
4.cos(α - β) - cos(α + β) = 2 sin α sin β

Please!!!!

Answer 1

is it
\[\large \tan(2u) \]
or
\[\large \tan^2u \]
?