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 