A quadrilateral is a closed, two-dimensional polygon with exactly four straight sides, four vertices, and four angles; it may vary in size, orientation, and side lengths. Identification depends on these defining attributes rather than appearance, so squares, rectangles, rhombi, trapezoids, and irregular four-sided figures can all qualify, while open shapes or figures with curved sides do not; formal angle measurement and proofs are beyond this understanding.
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Detailed Explanation: Identify quadrilaterals
A quadrilateral is a closed shape with exactly four straight sides. It also has four corners, called vertices, and four angles.
To identify one, check:
- Is the shape closed?
- Are all its sides straight?
- Does it have exactly four sides?
Worked example
Suppose a shape has points , , , and . Its sides are:
Check the shape:
- It is closed because the last side, , connects back to the starting point .
- All four sides are straight.
- It has exactly four sides and four corners.
Therefore, the shape is a quadrilateral. It does not matter whether it is tilted, has equal sides, or looks unusual. What matters is that it is closed and has exactly four straight sides.
Learn by doing: Identify quadrilaterals
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Practice:
Classifying Polygons by Sides
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Download/Modify Free Grade 3 'Identify quadrilaterals' Worksheet
Print this free 'Identify quadrilaterals' worksheet to practice this skill away from the computer. Click 'Modify' to easily customize this worksheet to your exact needs.
This Worksheet Includes:
- Classifying Polygons by Sides
- Quadrilaterals
- Classifying Polygons by Sides (Real World)
- Identify Shapes 2D - Count Trapezoids
- Polygons - Number of Sides to Name
- Polygons - Number of Sides to Name - First Time
- 2D Shapes by Side Count
- 2D Shapes by Vertex Count
Units Teaching This Skill
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