Question

Cos 2theta=2 (cos theta)^2 - 1
What is formula of cos theta = ??

Answer 1

Answer:

$cos \alpha = 2 {cos( \frac{ \alpha }{2} )}^{2} - 1$

Answer 2

Answer:

let theta=A

COS2A=2COS^2A -1

2COS^2A=1+COS2A

COS^2A

=(1+COS2A)/2

COSA=✓(1+COS2A)/2