$If tan^4a + tan^2a = 1$ , then find the value of $cos^4a + cos^2a ?$

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Answer 1 · 2016-12-26T08:38:25

Given

$tan^4a+tan^2a=1$

$=>(tan^2a+1)tan^2a=1$

$=>sec^2atan^2a=1$

$=>(1/cos^2a)tan^2a=1$

$=>tan^2a=cos^2a$

$=>sin^2a/cos^2a=cos^2a$

$=>sin^2a=cos^4a$

$=>1-cos^2a=cos^4a$

$=>cos^4a+cos^2a=1$

If tan^4a + tan^2a = 1If tan^4a + tan^2a = 1, then find the value of cos^4a + cos^2a ?cos^4a + cos^2a ?