Question

cos²(A+45)+cos²(a-45)=1​

Answer 1

Answer:

1

Step-by-step explanation:

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

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