a) sin^2x + cos^2x = 1 (identity)
b) sin^2x / (1 + cos^2x) = sin^2x (as the denominator cancels out)
c) cos^2x - cosx / (1 - sinx) = 0
d) No option provided
e) cos3x - cosx / sinx = 2cos^2x - 1 (via trigonometric identities)
a) sin^2x + cos^2x = 1 (identity)
b) sin^2x / (1 + cos^2x) = sin^2x (as the denominator cancels out)
c) cos^2x - cosx / (1 - sinx) = 0
d) No option provided
e) cos3x - cosx / sinx = 2cos^2x - 1 (via trigonometric identities)