A student was asked to prove the trigonometric identity tan- x + cot-x =2cscx. Which of the following could be the first step in proving the identity? 1 1- cos x sin x = 2cscx sin x 1- cos X sin x 1+ cos x = 2cscx 1+ cos x sin x 1 1-cosx 1-cosx = 2cscx sin x sin x Ol only O Il only O I and ll only OI, II, and Ill