Answer:
Cos²(45°—A) + cos²(45°+A)
= [2 cos²(45°—A) + 2 cos²(45°+A)] /2
= [{2 cos²(45°—A)—1} + {2 cos²(45°+A)—1} + 2] /2
= [cos2(45°—A)+cos2(45°+A)+2]/2
= [cos(90°—2A)+cos(90°+2A)+2]/2
= (sin2A—sin2A+2)/2
= 2/2
= 1
