`sqrt(2+sqrt(2+sqrt(2+.....sqrt(2(1+cos2^nA)))))=2cosA`

sqrt(2+sqrt(2+ sqrt(2+ sqrt(2+sqrt(2)....))))

Prove that: sqrt(2+sqrt(2+sqrt(2+2cos8A)))=2cosA

sqrt(2+sqrt(2+sqrt(2+sqrt(2+sqrt(2)))))=

sqrt(2+sqrt(2+sqrt(2+2cos8A)))=2cosA

sqrt(2+sqrt(2+sqrt(2+2 cos 8 theta)))=

sqrt 2(sqrt 2+1) - sqrt 2 (1+sqrt2) =?

Prove that sqrt(2+sqrt(2+sqrt(2+2 cos 8 theta)))=2 cos theta

2\ s in1^0 15 ' is equal to- a. \ sqrt(2-sqrt(2+sqrt(2))) b. \ sqrt(2-sqrt(2-sqrt(2))) c. sqrt((2+2sqrt(-sqrt(2)))/2) d. sqrt((2+sqrt(2+sqrt(2)))/2)