No doubt that Respected Cesareo R. Sir's Answer is the
easiest & shortest one, but, here is another way to solve it :
Let, #z=(1+sinx+icosx)/(1+sinx-icosx).#
Multiplying #Nr. and Dr.# by the conjugate of #Dr.,# we get,
Then, #z=(1+sinx+icosx)/(1+sinx-icosx)xx(1+sinx+icosx)/(1+sinx+icosx)#,
#=(1+sinx+icosx)^2/{(1+sinx)^2-i^2cos^2x}#,
#=(1+sinx+icosx)^2/{(1+sinx)^2+cos^2x}#,
Here, #"the Nr.="(1+sinx+icosx)^2,#
#=1+sin^2x-cos^2x+2sinx+2isinxcosx+2icosx,#
#=sin^2x+sin^2x+2sinx+2isinxcosx+2icosx,#
#=2sin^2x+2sinx+2isinxcosx+2icosx,#
#=2sinx(sinx+1)+2icosx(sinx+1),#
#=2(sinx+icosx)(sinx+1).#
And, #"the Dr.="(1+sinx)^2+cos^2x#,
#=1+2sinx+sin^2x+cos^2x,#
#=1+2sinx+1,#
#=2sinx+2,#
#=2(sinx+1).#
#rArr z={2(sinx+icosx)(sinx+1)}/{2(sinx+1)}#,
#=sinx+icosx.#
Q.E.D.
Enjoy Maths.!