You should yield to cars already in the traffic circle or roundabout, adhering to traffic rules designed to maintain safety and order on the roads.
When you are driving into a traffic circle (roundabout), you should yield to cars already in the circle. This is because vehicles inside the roundabout have the right of way, and entering traffic must wait for a safe gap before joining. Traffic signals and rules, like the one stating vehicles must stop at a red light, are intended to manage the flow of traffic and enhance safety by reducing speeds and providing clear guidelines on yielding and right of way.
Always yield to vehicles within the circle to ensure the safety and efficiency of the traffic system at roundabouts.