Question

cos 2x is equal to cos square x minus sin Square X proof​

Answer 1

Answer:

        cos(2x)= cos²x - sin²x

Step-by-step explanation:

we know

important identity,

cos(A + B) = cosA.cosB - sinA.sinB

Let A = x

B = x

cos(x + x) = cosx.cosx - sinx.sinx

cos(2x)= cos²x - sin²x

Hence proved