limx→0tan mxtan nx
=limx→0tan mxlimx→0tan nx
=limmx→0tan mxmx×mxlimnx→0tan nxnx×nx
[∵If x→0 then mx→also nx→0]
=1×m1×n [∵limx→0tanxx=1]
=mn
limx→0etanx−1tanx