Question

can someone show me how to exactly solve:

cos(1/8pi)

Answer 1

I know the answer is \[1/2\sqrt{2+\sqrt{2}}\]

Answer 2

cos(1/8pi) = 1/√2 * (√(1+cos(pi/4)) =1/√2 * (√(1+√2/2)

Answer 3

let (pi) be 180
therefore (1/8)pi=(1/8)180=cos(45/2)=1/2sqrt(2+sqrt2)
as the final answer u posted

Answer 4

@matricked
i dont understand why cos(1/8pi) can be written as 1/√2 * (√(1+cos(pi/4))
can you say which basic formulas or assumptions you use to do this?

Answer 5

of i am not wrong i have used cos2t = 2(cost)^2 -1
hope u got it