Sqrt 32-sqrt 128*sin^2 (9π/8)

Question

Sqrt 32-sqrt 128*sin^2 (9π/8)

Answer 1

√32 - √128sin²(9π/8) = √32(1 - 2sin²π/8) = √32(cos2π/8) = 4√2*cos(π/4) =
= 4√2*(√2/2) = 4