Question

8cos7°30' =

$4 + \sqrt{6} + \sqrt{2}$
​

Answer 1

Answer:

Step-by-step explanation:

cos π/8  cos 3π/8  cos 5π/8  cos 7π/8

  =  (cos π/8  cos 7π/8) ( cos 3π/8  cos 5 π/8)

  =  [cos 6π/8 - cos 8π/8]/2  [ cos 2π/8 - cos 8π/8]/2

  =  [- 1/√2 + 1 ] [1/√2 + 1] / 4

    = (1 - 1/2 ) /4

  = 1/8