cot(90o−θ)sin(90o−θ)sin θ+cot 40otan 50o−(cos2 20o+cos2 70o) = ?
(a) 0 (b) 1 (c) -1 (d) none of these
cot(90o−θ)sin(90o−θ)sin θ+cot 40otan 50o−(cos2 20o+cos2 70o)
=tanθ×cosθsin θ+cot 40ocot(90−50)o−(cos2 20o+sin2(90−70)o)
=sinθcosθ×cosθsin θ+cot 40ocot40o−(cos2 20o+sin2 20o)
=1+1−1=1