Correct me if I'm wrong, but I understood that 14 cm is the length of the line segment drawn across the circle. We know that the definition of the diameter is "any straight line segment that passes through the center of the circle and whose endpoints lie on the end of each circle", which can be defined as the line that is shown with a length of 14 cm. It is also known that the radius, a line drawn from the center of the circle to an endpoint, is always half of the diameter, which in this case is 14 cm, so the radius would be 7 cm.
