You can put this solution on YOUR website! How can do you prove that
secx - (tanx)(sinx) = cosx?
Start with left side:
secx-(tanx)(sinx)
=(1/cosx)-(sinx/cosx)sinx
=(1/cosx)-sin^2x/cosx
=(1-sin^2x)/cos)
=cos^2x/cosx
=cosx
verified: left side=right side