A
two-dimensional figure is a figure without thickness; it is flat.
A
polygon is a two-dimensional figure
made up of non-overlapping, straight line segments.
The point where two line segments meet is a
vertex.
triangle | quadrilateral | pentagon | hexagon | heptagon |
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3 sides 3 vertices | 4 sides 4 vertices | 5 sides 5 vertices | 6 sides 6 vertices | 7 sides 7 vertices |
octagon | nonagon | decagon | undecagon | dodecagon |
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8 sides 8 vertices | 9 sides 9 vertices | 10 sides 10 vertices | 11 sides 11 vertices | 12 sides 12 vertices |