The purple line is tangent. Tangent line intersects a circle in only 1 point The yellow dot is the point of tangency. It is the point where tangent line touches the circle The light blue line is secant. Secant line intersects a circle in 2 points The red line is the radius. Radius is the distance from center to the outer rim of the circle. The green line is the diameter. It is the line passing through the center of a circle. It measures twice the radius The gray line is the chord. Chord is the line whose endpoints lie on the circle. Arc AB is a minor arc Arc ABCD is a major arc