Points, Lines, Segments, Rays, Angles, Polygons and Circles

Octagon

• a quadrilateral whose opposite sides are parallel

• a line segment containing the center of the circle, with endpoints on the circle

• unit for measuring angles

• a polygon with eight sides

Nonagon

• angles that have the same measure

• a figure consisting of two points on a circle and the continuous part between the points

• a polygon with eight sides

• a polygon with nine sides

Decagon

• a quadrilateral whose opposite sides are parallel

• A line segment with one endpoint at the center of a circle and the other endpoint on the circle

• a polygon with ten sides

• a polygon with with six sides

Undecagon

• a quadrilateral with two pairs of distinct congruent sides. The congruent sides share a vertex.

• two lines that do not intersect and are non-coplanar

• a ray that contains the vertex of an angle and divides the angle into two congruent angles

• a polygon with eleven sides

Dodecagon

• a polygon with twelve sides

• (3) pairs of angles, segments, or polygons are congruent - they must be marked with congruency symbols, which show that they're congruent

• a quadrilateral whose opposite sides are parallel

• having the same value

Concave Polygon

• a polygon where at least one diagonal is outside the polygon

• a line segment that connects two nonconsecutive vertices of a polygon

• A polygon where no diagonal is outside the polygon

• a line segment containing the center of the circle, with endpoints on the circle

Things you can't assume:

• Lines are straight.

• Pairs of angles, segments, or polygons are congruent - they must be marked with congruency symbols, which show that they're congruent

• Two lines are parallel just because they look parallel - they must be marked using parallel symbols

• Two lines are perpendicular just because they look perpendicular - they must be marked with a 90º symbol

• Points on a line are collinear and all points shown on a diagram are coplanar.

Circle

• A figure that is formed by the set of all points in a plane at a given distance from a given point in the plane.

• a polygon that is both equilateral and equiangular

• a polygon with three sides.

• (3) points on a line are collinear and all points shown on a diagram are coplanar.

Radius

• a triangle with no congruent sides

• a polygon with equal angles and equal sides

• A line segment with one endpoint at the center of a circle and the other endpoint on the circle

Diameter

• two angles that are formed by intersecting lines. The angles share a vertex, but not a common side.

• a line segment containing the center of the circle, with endpoints on the circle

• two lines that intersect to form a right angle

• a polygon with seven sides