Basic Geometry Terms

Ray

• A part of a line that starts at a point and goes infinitely in one direction.

• A straight line that connects two points.

• A line that has a fixed length and does not extend.

• A curve that bends in one direction.

Supplementary Angles

• Two angles whose measures add up to 180 degrees.

• Two angles whose measures add up to 180 degrees.

• Two angles that are equal in measure.

• Two angles that are adjacent to each other.

Complementary Angles

• Two angles whose measures add up to 90 degrees.

• Two angles whose measures add up to 180 degrees.

• Two angles that are equal in measure.

• Two angles that are adjacent to each other.

Acute Angle

• An angle that is less than 90 degrees.

• An angle that is exactly 90 degrees.

• An angle that is greater than 90 degrees but less than 180 degrees.

• An angle that is equal to 180 degrees.

Line

• A straight line going infinitely in both directions.

• A curved path that bends and twists.

• A segment of a line with two endpoints.

• A collection of points that form a closed shape.

Point

• A specific location represented by a dot.

• A line segment connecting two points.

• A shape with three sides.

• A solid figure with length, width, and height.

Perpendicular Lines

• Two lines that intersect at a right angle (90 degrees).

• Two lines that never intersect.

• Two lines that intersect at an acute angle.

• Two lines that are parallel to each other.

Protractor

• A tool used to measure and draw angles.

• A device for measuring temperature.

• An instrument for measuring time intervals.

• A tool for cutting shapes.

Vertex

• The common endpoint of two or more rays or line segments.

• A type of angle measurement.

• The longest side of a triangle.

• A point in a geometric figure that is not connected to any lines.

Obtuse Angle

• An angle that is greater than 90 degrees but less than 180 degrees.

• An angle that is exactly 90 degrees.

• An angle that is greater than 90 degrees but less than 180 degrees.

• An angle that is greater than 180 degrees.