1.

sin4 θ + 2 cos2 θ \(\bigg(1-\frac{1}{sec^2\,\theta}\bigg)\) + cos4 θ =(a) 1 (b) 2 (c) √2 (d) 0

Answer»

(a) 1

sin4 θ + 2 cos2 θ \(\bigg(1-\frac{1}{sec^2\,\theta}\bigg)\) + cos4 θ

= sin4 θ + 2cos2 θ (1 cosθ) + cos4 θ 

= sin4 θ + 2cos2 θ. sin2 θ + cos4 θ 

= (sin2 θ + cos2 θ)= 12 = 1



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