Sec^2 2u-1/Sec^2 2u = Sin^2 2u

2 answers

since all angles are 2u , let Ø - 2u for ease of typing

I will assume you are proving this as an identity

LS = (1/cos^2 Ø - 1)/(1/cos^2 Ø)
= (1 - cos^2 Ø)/cos^2 Ø * (cos^2 Ø)
= 1 - cos^2 Ø
= sin^2 Ø
= RS

replace Ø with 2u if you have to
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