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Angle

Formed by two rays that have the same endpoint

Vertex

Where two endpoints meet

Interior

Inside of an angle

Exterior

Outside of an angle

Acute Angle

Less than 90 degrees

Obtuse Angle

More than 90 degrees

Right Angle

Exactly 90 degrees

Straight angle

Exactly 180 degrees

Center

Middle of circle

Diameter

Connects from one side to another

Radius

Connects from one side to the center

Chord

Any line segment that connects to two point

Central Angle

An Angle whose vertex is in the center

Polygon

A closed plain figure

Regular Polygon

A polygon with equal sides in length

Triangle

A polygon with three sides

Eqaulateral Triangle

A triangle with all sides the same length

Isosoeles Triangle

A triangle with only two sides the same length

Scalene Triangle

of a triangle having three sides of different lengths

Right Triangle

A triangle with one right angle

Acute Triangle

A triangle that has three acute angles

Obtuse Triangle

A triangle with one obtuse angle

Quadrilateral

a four-sided polygon

Pentagon

A five-sided polygon

Hexagon

A six-sided polygon

Octagon

An eight-sided polygon

Parallelogram

A quadrilateral whose opposite sides are both parallel and equal in length

Rectangle

A quadrilateral with four right angles

Square

A rectangle with all sides the same length

Rhombus

A parallelogram with all sides same length

Trapazoid

Quadrilateral with one pair of opposite sides parallel

Similar Figures

Figures that have the same shape but not necessarily the same size

Congruent Figures

Figures that have the same size and shape

Point

An exact spot on a line or dot

Line

A straight mark that never ends

Ray

A straight line extending from a point

Perpendicular Lines

Lines that intersect to form right angles

Intersecting Lines

Lines that meet but don't form right angles

Parallel

Two lines that will never intersect