cos (2π-a) × cos(2π +a) - sin2a = cos^2(2π) - sin^2(a)Since cos(2π) = 1 and sin(a) = 0 for all integer values of a, the expression simplifies to:
1 - 0 = 1.
cos (2π-a) × cos(2π +a) - sin2a = cos^2(2π) - sin^2(a)
Since cos(2π) = 1 and sin(a) = 0 for all integer values of a, the expression simplifies to:
1 - 0 = 1.