Polygons and circle

• circle is a set of points in a plane that are equidistant from a fixed point called the

  center.
• The distance around the circle is called the circumference.
• center is connected to any point on the circle by a line segment called radius (plural:radii).
• By constructing two radii in the circle, a central angle can be formed.
• The set of points along the circle connecting two radii is called an arc.
• An arc that is half of the circumference is called a semicircle.
• Major arcs are arcs longer than a semicircle,
• minor arcs are shorter than a semicircle
• line segment connecting two points on the circle is called a chord.
• When a chord passes through the center, that chord becomes a diameter of a circle.
• line that intersects the circle at two points is called a secant of the circle.
• When a line touches the circle at one and only one point, it is called a tangent
• The point at which the tangent and the circle touch is called the point of tangency.
• An angle formed by two chords whose vertex is on the circle is called an inscribed angle.