Verify that (cos^2x - sin^2x) / (1-tan^2x) = cos^2x ?

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Answer 1 · 2016-11-12T08:42:17

see below

$(cos^2x-sin^2x)/(1-tan^2x) = cos^2x$

Left Side: $=(cos^2x-sin^2x)/(1-tan^2x)$

$=(cos^2x-sin^2x)/(1-sin^2x/cos^2x)$

$=(cos^2x-sin^2x)/((cos^2x-sin^2x)/cos^2x)$

$=cancel(cos^2x-sin^2x) cos^2x/cancel(cos^2x-sin^2x)$

$=cos^2x$

$:.=$ Right Side