SA3 marksYear: 2024HardCBSE Class 10
trigonometryidentityproof
Question
Prove that:
1−cotAtanA+1−tanAcotA=1+secAcscA
Solution
1
LHS =sinAsinA−cosAcosAsinA+cosAcosA−sinAsinAcosA
+0.5 marks2
=sinA−cosA1[cosAsin2A−sinAcos2A]
+1 mark3
=sinA−cosA1×sinAcosA(sinA−cosA)(sin2A+cos2A+sinAcosA)
+1 mark4
=sinAcosA1+sinAcosA=sinAcosA1+1=1+secAcscA = RHS
+0.5 marks