SA3 marksYear: 2025MediumCBSE Class 10
trigonometrytrigonometric-identitiesproof
Question
Prove that: cscθ+1cscθ−1+cscθ−1cscθ+1=2secθ Solution
1
LHS =cscθ+1cscθ−1+cscθ−1cscθ+1
=(cscθ+1)(cscθ−1)(cscθ−1)+(cscθ+1) +1 mark2
=csc2θ−12cscθ=cotθ2cscθ +1 mark3
=sinθcosθ2⋅sinθ1=cosθ2=2secθ = RHS
+1 mark