SA3 marksYear: 2023HardCBSE Class 10
trigonometryidentitiesproof
Question
Prove that:
1−cotθtanθ+1−tanθcotθ=1+secθcosecθ
Solution
1
LHS =1−sinθcosθcosθsinθ+1−cosθsinθsinθcosθ
+1 mark2
=cosθ(sinθ−cosθ)sin2θ+sinθ(cosθ−sinθ)cos2θ
+1 mark3
=sinθcosθ(sinθ−cosθ)sin3θ−cos3θ
+0.5 marks4
=sinθcosθsin2θ+sinθcosθ+cos2θ=sinθcosθ1+1=1+secθcosecθ = RHS
+0.5 marks