If sec 4x-sec2x = 2, find the value of cos^2x, 0<x<pi/2

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- December 6th 2009, 03:20 PMKingV15Trig Functions
If sec 4x-sec2x = 2, find the value of cos^2x, 0<x<pi/2

- December 6th 2009, 07:50 PMSoroban
Hello, KingV15!

We need two identities: .

Quote:

If , find the value of

We have: .

. .

. .

. .

Then:

. .

. .

From [1]: .

From [2]: .