Question

If sinA + sin^2 A = 1, then the value of the expression (cos^2 A + cos^4 A) is (A) 1 (B) 1/2 (C) 2 (D) 3

Answer 1

sinA=1-sin2A
=cos2A
cos2A+cos4A
cos2A+(cos2A) ^2
sinA+sin2A
1