# Geometry terms and definitions

To save you having to refer to a dictionary, we’ve listed below some of the more common geometry terms and geometry definitions to help you help with your child’s geometry homework.

#### Definition/ Description

Point A location in space - a dot on a piece of paper
Line Connects two points via the shortest path and continues indefinitely (forever) in both directions Line Segment Part of a line between two points Perpendicular Line Segment Line Segments that intersect (cross) at an angle of 90° Parallel Line Segments Line segments that never intersect (they are always the same distance apart) Right Angle An angle that measures 90° Acute Angle An angle that measures less than 90° Obtuse Angle An angle that measures more than 90° Vertex Point at which two line segments intersect (forming an angle) Scalene Triangle A triangle with all three sides with different lengths Isosceles Triangle A triangle with two equal length sides (and two equal internal angles) Equilateral Triangle A triangle with all three sides of equal length (each internal angles = 60°) Radius Distance (line segment) from center of a circle to any point on that circle's circumference. Diameter A line segment (or length) joining two points on a circles circumference and passes through the circle's center (twice the length of the radius) Circumference Distance around a circle (the perimeter) Chord A line segment joining two points on a curve. Arc Part of a curve This Math Open Reference Project provides additional information with more geometry terms and definitions.

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