Q320
sin4θ + cos4θ in terms of sinθ can be written as:
A.
2sin4θ + 2sin2θ - 1
B.
2sin4θ - 2sin2θ
C.
2sin4θ - 2sin2θ - 1
D.
2sin4θ - 2sin2θ + 1
AnswerAnswer: Option D
Solution
Answer: Option D
Solution:
(sin2θ + cos2θ)2 = 1sin4θ + cos4θ + 2sin2θ.cos2θ = 1
sin4θ + cos4θ = 1 - 2sin2θ.cos2θ
sin4θ + cos4θ = 1 - 2sin2θ(1 - sin2θ)
sin4θ + cos4θ = 1 - 2sin2θ + 2sin4θ