Definition
Pentagon
A pentagon is a flat, closed shape made from exactly five straight sides.
Continue from this idea into connected AXIO math.
What it means
Trace the boundary and count each straight side once. If the line closes after side 5, it is a pentagon. A pentagon can be skinny, wide, tilted, or uneven.
Remember it
Penta means five: five straight sides make the border.
Example
A badge outline has side lengths 2, 3, 4, 3, and 2 cm. The border closes after five straight sides, so it is a pentagon even though the lengths are different.
Watch for
The outside edge of a typical five-point star has ten sides, so that outline is not a pentagon.
Common mix-up
Five equal sides are not required. Equal sides and equal angles are extra conditions for a regular pentagon.
Exact meaning
A pentagon is a polygon with five straight sides and five vertices. Its side lengths and angles may vary, so a pentagon does not have to be regular.