Geometric Terms


ShapeTermDefinition
perpendicular line segments Two line segments which cross to form 90 degree angles.
right angle A 90 degree angle.
equilateral triangle A triangle with all sides equal and all angles equal.
scalene triangle A triangle having three unequal sides and angles.
vertex The intersection point of two sides of a plane figure.
right triangle A triangle with one internal angle equal to 90 degrees.
pentagon A polygon with 5 sides and 5 angles.
square A rectangle having all four sides of equal length.
intersecting line segments Line segments that cross each other.
acute angle An angle less than 90 degrees but greater than 0 degrees.
chord The line segment between two points on a given curve.
radius A straight line extending from the center of a circle or sphere to the circumference or surface.
line segment One part of a line.
line A continuous extent of length.
point A position in space.
parallelogram A quadrilateral having both pairs of opposite sides parallel to each other.(Note: squares and rectangles are also quadrilaterals.)
rectangle A parallelogram having four right angles.(Note: a square is also a rectangle.)
rhombus An equilateral parallelogram having oblique angles.
parallel line segments Line segments that do not intersect.
quadrilateral A polygon with four sides.(Note: squares, rectangles and trapezoids are also quadrilaterals.)
octagon A polygon having eight angles and eight sides.
circle A closed plane curve consisting of all points at a given distance from a point within it called the center.
trapezoid A quadrilateral plane figure having two parallel and two nonparallel sides.
ray The part of a straight line considered as originating at a point on the line and as extending in one direction from that point.
closed curve A curve that is continuous and has endpoints that meet at the same point.
isosceles triangle A triangle which has two sides equal.
hexagon A polygon having six sides and six angles.
diameter A straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end.
obtuse angle An angle greater than 90 degrees but less than 180 degrees.