Geometry Terms

collinear

points lying in the same straight line

coplanar

in the same plane

convex polygon

a closed, flat shape with straight sides where all its internal angles are less than 180 degrees

concave polygon

a closed, straight sided shape with at least one interior angle greater than 180 degrees

regular polygon

all sides of equal length and all interior angles of equal measure

irregular polygon

sides and angles are not equal

penta

5

hexa

6

hepta

7

octa

8

nona

9

deca

10

equilateral

having all of its sides the same length

equiangular

having equal angles

bisect

to divide a line segment, angle, or shape into two equal or congruent parts

rotational symmetry

Rotational symmetry (or radial symmetry) occurs when a shape, after being rotated less than 360 around a central point, matches its original position

reflectional symmetry

occurs when one half of a shape or object is an exact mirror image of the other half, divided by a line called the axis or line of symmetry

scalene triangle

a polygon with 3 unequal sides and angles