Security Cameras

Below are six rooms, as seen from above. Your task is to place the minimum number of security cameras need in each room, so that all parts of the room can be monitored. For each room, mark where the camera(s) should be placed using a point.

Can you find a relationship between the number of corners (or vertices) in a room and the number of cameras required? Try to use this observation to find the maximum number of cameras that may be needed for a room given the number of vertices. Hint: Try drawing rooms with different shapes.