# Help Zone

### Student Question

Secondary I • 1yr.

Hi! What distinguishes triangles from quadrilaterals other than their number of sides ?

Mathematics

## Explanations (1)

• Explanation from Alloprof

Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

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Team Alloprof • 1yr.

Hello,

the answer to this question can be very elaborate.

There are numerous similarities: they are polygons (closed chain), they have sides (segments of lines), angles, vertices (corners), etc. There are a lot of differences as well, besides the number of sides which is not the same:

-A quadrilateral has 4 vertices. A triangle, 3.

-A quadrilateral has 4 interior angles. A triangle, 3.

-A quadrilateral has 4 exterior angles. A triangle, 3.

-The sum of the measures of the interior angles of a quadrilateral is 360 °. That of a triangle is 180 °.

-A quadrilateral has 2 diagonals. A triangle, 0.

-A quadrilateral can be crossed. A triangle, no.

-A quadrilateral can be convex or non-convex (concave). A triangle is always convex.

-There are quadrilaterals that are equilateral but not equiangular (diamonds, and some quadrilaterals that are equiangular but not equilateral (rectangles). Equilateral triangles are always equiangular and vice versa.

etc.

My pleasure!