noun
triangle
TRY-ang-guhl/ˈtraɪæŋɡl/
A plane figure with three straight sides.
The thin terracotta-colored card forms a triangle with three straight sides.
Etymology
The pieces mean “three-cornered”: the name identifies the figure by its three angles. Those corners are where its three straight sides meet.
In context
two angles determine the shape of the triangle
More examples
- An equilateral triangle has three equal sides.
- She cuts a triangle out of blue paper.
- A diagonal divides the rectangle into two triangles.
Forms
triangle · triangles
triangular adjective — Having the shape of a triangle.
Similar words
- polygon
- A broader term for closed figures with straight sides.