Question

prove that:(2 cos a + 1) (2 cos a - 1) (2 cos 2a - 1) = 2 cos 4a + 1​

Answer 1

Answer:

true

Step-by-step explanation:

first take (2cos a + 1)(2cos a - 1)

use formula (a+b)(a-b) we get a^2 - b^2

then use formula cos2x = 2(cos x)^2 -1

further simplify it and use the same method for 3rd expression 2(cos 2a) -1