Prove the following identities

cosx (tanx + 2) (2 tanx + 1) = 2 secx + 5 sinx

LHS = cosx (tanx + 2) (2 tanx + 1)


= cosx (2 tan2x + 5 tanx + 2)



We know that





= 2 secx + 5 sinx


= RHS


Hence proved.


16