cscx/(cotx+tanx) = cscx/(1/tanx + tanx)
= cscx/[(1+tan2x)/tanx]
= cscx/[sec2x/tanx]
= (cscx)(tanx)/sec2x
= (cscx)(tanx)(cos2x)
= (1/sinx)(sinx/cosx)(cos2x) = cosx