Geometry Unit 1 Vocabulary

Front

Found on the same plane

Back

Coplanar: Points or lines that lie on the same flat surface.

Front

Lines that meet at 90° angles

Back

Perpendicular Lines: Lines that intersect to form a right angle.

Front

A 90° angle

Back

Right Angle: An angle that measures exactly 90 degrees.

Front

A flat surface with two dimensions: length and width

Back

Plane: A two-dimensional surface that extends infinitely in all directions.

Front

A figure comprised of two rays and a common endpoint

Back

Angle: Formed by two rays that share a common endpoint called the vertex.

Front

Lines that never intersect and are always the same distance apart

Back

Parallel Lines: Lines in a plane that do not meet; they are equidistant from each other.

Front

The point where two lines intersect

Back

Intersection: The point at which two lines cross each other.

Front

A straight line that extends infinitely in both directions

Back

Line: A one-dimensional figure that has no thickness and extends infinitely.

Front

A part of a line that has a fixed starting point and extends infinitely in one direction

Back

Ray: A part of a line that starts at a point and goes off in a particular direction.

Front

A polygon with four sides and four angles

Back

Quadrilateral: A four-sided figure.