Verified answer

= (sec^2u - 1 + 1 - sin^2u)/(secu + sin u) = (sec^2u - sin^2u)/(secu + sinu)

=(secu + sinu)(secu - sinu)/(secu + sinu) = secu - sinu.

step by step solution

http://symbolab.com/solutions/proving_identities?q...