Question

2cos^2 (x) = 1 + cos 2x ------ HOW?

Answer 1

HELLO DEAR,


COS(2X) = COS(x + x)
∴[cos(a + b) = cos.cosb - sina.sinb]

Cosx.cosx - sinx.sinx = cos²x - sin²x

Cos²x - (1 - cos²x)
∴[sin²Ф + cos²Ф = 1]

Cos²x + cos²x - 1 = (2cos²x - 1)


Now,


1 + cos2x = 1 + 2cos²x - 1 = 2cos²x


I HOPE ITS HELP YOU DEAR,
THANKS