Defining and Identifying the Radius of a Circle

MatholiaChannel

This concise animated mathematics tutorial defines and demonstrates the concept of a radius within a circle. The video begins by clearly defining a radius as a straight line connecting the center of a circle to its circumference. It visually demonstrates drawing multiple radii (labeled OA and OB) from a central point, introducing the correct plural terminology "radii" to expand student vocabulary. The second half of the video transitions into an interactive misconception check, presenting viewers with three different lines originating from the center. It systematically analyzes each line to determine if it meets the criteria of a radius, explicitly showing why lines stopping short of the edge or extending beyond it are incorrect. This non-example approach helps solidify the precise geometric definition. For educators, this resource serves as an excellent introduction to circle geometry or a review of key vocabulary. The clear visual distinction between correct and incorrect examples makes it particularly useful for addressing common student errors in geometric drawing. It lays the groundwork for understanding related concepts like diameter, circumference, and area.