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.