cos^4a-sin^a is equal to _______
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cos^4a-sin^a is equal to _______
(cos^2a)^2 - (sin^2a)^2
(cos^2a - sin^2a)(cos^2a+sin^2a)
As we know that
cos^2a+sin^2a=1
cos^2a - sin^2a=cos 2a
hence,
cos^4a-sin4a = cos2a
(cos^2a)^2 - (sin^2a)^2
(cos^2a - sin^2a)(cos^2a+sin^2a)
As we know that
cos^2a+sin^2a=1
cos^2a - sin^2a=cos 2a
hence,
cos^4a-sin4a = cos2a
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