Can we attach 2 separate LAN with repeater?

Can we attach 2 separate LAN with repeater ?

 The repeater is used to extend the segment length but not to connect the systems to it suppose two building away from each other having distance more than 100 meter than we have to use repeater in between the cable used to connect the rooms. We cannot attach two different LAN with the repeater but we have to use the router for this purpose.