Which expression is not equivalent to cos 2 (theta) for all values of theta?

Question

A. cos^2 (theta)-sin^2(theta)

 

B. 2sin (theta)cos (theta)

 

C. 1-2sin^2 (theta)

 

D. 2cos^2 (theta)-1

Answer 1

Greetings! Lets solve this shall we ?

So, we must yield the Trigonometric Identities such that

cos(2θ) = cos²θ - sin²θ

= 2cos²θ - 1

= 1 - 2sin²θ

Therefore, the one not equivalent to this is B

I hope this helped!