Is the given equation an identity? cos ⁡ 2 x ( 1 + tan ⁡ 2 x ) − 1 = 0 \cos^2x\left(1+\tan^2x\right)-1=0 cos 2 x ( 1 + tan 2 x ) − 1 = 0

Introduction to Trigonometric Identities

6. Trigonometric Identities and More Equations / Introduction to Trigonometric Identities / Problem 6

Is the given equation an identity?
$\cos^2x\left(1+\tan^2x\right)-1=0$

Yes