Question

If alpha + beta = 90° then cos2alpha + cos2beta equals to:
(A) 1/2 (B) 0 (C) 2 (D) 1

Answer 1

hey mate here is ur ans

alpha= x

beta= y

x+y= 90° y= 90°-x

cos2x+cos2y = cos2x+cos2(90°-x)

= cos2x-cos(180°-2x)

= cos2x-cos2x = 0

B is correct option

hope it help u

Answer 2

Answer:answer is option number d–(1)

alpha+beta =90⁰,

cos²alpha +cos²beta=

cos²alpha+cos(90⁰–alpha)=cos²alpha+sin²alpha=1

HOPE IT MAY HELP YOU