Types of Quadrilaterals
Drag the four corners. The shape earns its name as the sides line up. Bend it however you like: the four angles inside still add to 360°.
Parallelogram
Both pairs of opposite sides are parallel.
Angles 72° + 108° + 72° + 108° = 360°
Jump to a shape
Ready to try some? Quadrilateral worksheets
Where it usually goes wrong
The names are treated as a row of separate boxes, so a square is said not to be a rectangle. They are nested: a square is a rectangle that got lucky twice, and a rectangle is a parallelogram with square corners. The other half of the trouble is thinking the angle sum depends on the shape — it does not, and no amount of bending changes it.
Try this
- Press Square, then drag one corner. Watch which name it earns as the sides stop being equal, and which facts survive.
- Bend it into a kite, then into something with no name at all. The four angles still total 360°.
- Try to make a shape whose angles total anything else. Four corners cannot do it, which is the whole point of the number.
Where this goes next
Every polygon has an angle sum found the same way — by cutting it into triangles — and a quadrilateral is two triangles, which is exactly why it comes to 2 × 180°.