For scalable information routing and dissemination, broadcast has been gaining tremendous interests of research in Wireless Sensor Networks (WSNs), where each sensor node has inherent resource constraints in terms of battery energy, and computing and communication capabilities. Since a blind broadcast can cause the broadcast storm problem, diverse broadcast strategies have been explored to increase the network coverage but to minimize the redundant rebroadcasts. In this paper, we propose a geometric broadcast scheme in dense WSNs. This scheme deploys a sender-initiated broadcast approach, where a sender approximates the location of its neighbor nodes without using an on-board global positioning system (GPS). Then the sender selects a set of forwarding candidate nodes located at the closest to the strategic positions based on a virtual hexagon-based coverage. A simple random backoff mechanism is also proposed to reduce the packet contentions and collisions. We develop a customized discrete-event driven simulator using the OMNeT++ to conduct our experiments. Two well-known broadcast schemes are modified to work in dense WSNs: Flooding and Ad Hoc Broadcast Protocol (AHBP). We conduct an extensive performance comparison study and the proposed scheme achieves a competitive and scalable performance in dense WSNs.