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August 28, 2015
Posted by **Rosilyn** on Saturday, October 8, 2011 at 2:21pm.

Sec^4x - Tan^4x = Sec^2x + Tan^2x

- math -
**Reiny**, Saturday, October 8, 2011 at 4:46pmLS = (sec^2 x - tan^2x)(sec^2x + tan^2x)

= (1 + tan^2x - tan^2x)(sec^2x + tan^2x)

= 1(sec^2x + tan^2x)

= RS