Geometric Terms

shape term definition
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