Parts of a Circle

• Circle - the set of points in a plane equidistant form a given point (the center of the circle)
• Radius - the distance from the center to a point on the circle
• Circumference - the distance around the edge of the circle
• Congruent Circles - two circles with the same radius
• Diameter - a segment that goes through the center of the circle, with both endpoints on the edge of the circle (divides the circle to 180°)
• Chord - a line segment that goes from one point to another on the circle's circumference
• Tangent - a line that intersects a circle at only one point. The radius at the poing of tangency is perpendicular to the tangent line
• Secant - a line that intersects a circle at two points
• Inscribed Angle - an angle made from points sitting on the circle's edge
• Central angle - an angle with vertex at the center of the circle and is formed by its endpoints
• Arc - part of the circumference (edge) of the circle and is equal to the measure of an angle
• Minor Arc - measures less than 180°
• Major Arc - measures more than 180°
• Semicircle Arc - measures exactly at 180°
• Sector - a portion of an angle enclosed by two radii and an arc