Question

If sinA + sin2 A = 1 then the value of expression of cos2 A + cos4 A is
(a) 1/2
(b) 1
(c) 2
(d) 3
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Answer 1

Answer:

1........................

Answer 2

Answer:

sinA= 1-sin2A

sinA=cos2A

put the value of sinA in eq 1

cos2A+cos4A=1