Question

Verify sin^4x-sin^2x=cos^4x-cos^2x is an identity. Please dumb it down, i don't get this lesson.

Answer 1

Explanation:

cos^2+sin^2 = 1 ( rule)

cos^4x-cos^2x simplify

- cos^2( -cos^2 +1 ) -cos^2 common

or -cos^2 ( 1-cos^2)

since cos^2 + sin^2 = 1

substitute : -cos^2 ( sin^2 )

substitute : -(1-sin^2 ) ( sin^2)

multiply : -sin^2 + sin^4 or sin^4 - sin^2

it is verified that sin^4 -sin^2= cos^4-cos^2

hope it helps