Geometry Vocabulary Terms with Pictures
Point
An exact location in space, usually represented by a dot
Angle
A figure formed by two rays that have a common endpoint
Vertex
The point where two or more rays meet; the point of intersection of two sides of a polygon; the point of intersection of three or more edges of a solid figure; the top point of a cone; the plural of vertex is vertices
Circle
A closed plane figure with all points on the figure the same distance from the center
Radius
A line segment with one endpoint at the center of a circle and the other endpoint on the circle
Obtuse Triangle
A triangle that has one obtuse angle
Polygon
A closed plane figure formed by three or more line segments
Square
A rectangle with 4 equal sides
Pentagon
A polygon with five sides
Line
A straight path in a plane that goes on forever in opposite directions
Right Angle
An angle formed by perpendicular lines, line segments, or rays and with a measure of 90°
Parallel Line
Lines in a plane that never intersect
Circumference
The distance around a circle
Triangle
A polygon with three sides
Equilateral Triangle
A triangle with three congruent sides
Parallelogram
A quadrilateral whose opposite sides are parallel and congruent
Trapezoid
A quadrilateral with one pair of parallel sides
Closed Figure
A figure that begins and ends at the same point
Line Segment
A part of a line that includes two points, called endpoints, and all of the points
Acute Angle
An angle that has a measure less than a right angle (less than 90°)
Perpendicular Lines
Two lines that intersect to form four right angles
Chord
A line segment with its endpoints on a circle
Right Triangle
A triangle with one right angle
Isosceles Triangle
A triangle with two congruent sides
Quadrilateral
A polygon with four sides
Hexagon
A polygon with six sides and six angles
Ray
A part of a line, with one endpoint, that continues without end in one direction
Obtuse Angle
An angle whose measure is greater than 90° and less than 180°
Intersecting Lines
Lines that cross at exactly one point
Diameter
A line segment that passes through the center of
a circle and has its endpoints on the circle
Acute Triangle
A triangle in which all three angles are acute
Scalene Triangle
A triangle with no congruent sides
Rectangle
A parallelogram with four right angles
Octagon
A polygon with eight sides