How to Classify Polygons: A Step-by-Step Guide to Shape Identification

Polygons are classified by side count and by regularity. A polygon is regular when all its sides and all its angles are equal, and convex when no interior angle exceeds 180 degrees.

• Triangle (3 sides)
• Quadrilateral (4 sides)
• Pentagon (5 sides)
• Hexagon (6 sides)
• … and so on.

• Equilateral: All sides are of equal length.
• Isosceles: Two sides are of equal length.
• Scalene: No sides are of equal length.

• Regular Polygon: All interior angles are equal.
• Irregular Polygon: Not all interior angles are equal.

• Square: All sides are equal, and all angles are right angles.
• Rectangle: Opposite sides are equal, and all angles are right angles.
• Rhombus: All sides are equal, but not all angles are right angles.
• Parallelogram: Opposite sides are equal and parallel.
• Trapezoid: Only one pair of opposite sides is parallel.

Examples

Practice questions on classifying polygons

1. A polygon has seven sides. What is it called?
2. If a quadrilateral has all its sides equal but not all angles are right angles, how would you classify it?
3. What differentiates a square from a rhombus?

1. A polygon with seven sides is called a heptagon.
2. A quadrilateral with all its sides equal but not all angles being right angles is a rhombus.
3. Both a square and a rhombus have all sides equal. However, a square has all right angles while a rhombus does not necessarily have right angles.

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