verify the identity tanx times cotx/cosx=secx
tanx(cotx/cosx)=secx
tanx(1/tanx)(1/cosx)=secx
cross out tanx with (1/tanx) and your left with (1/cosx) which is secx.
tanx(1/tanx)(1/cosx)=secx
cross out tanx with (1/tanx) and your left with (1/cosx) which is secx.