Question

What is the value of 2cos2(75°) – 1?

Answer 1

A. -(square root of 3 over 2)

Explanation:

got it right on edge :)

Answer 2

Option (1)

Explanation:

2cos²(75°) - 1 = cos2(75°) [By using identity 2cos²a - 1 = cos2a]

= cos(150°)

= cos(90 + 60)°

= -sin(60°) [Since, cos(90 + θ) = -sinθ]

=
`-(√(3))/(2)`

Therefore, solution of the given expression is
`(-(√(3))/(2))`.

Option (1) will be the correct option.