Because they are less expensive than quadrangles.
Possibilities are: triangles, pentagons, and quadrangles.
Triangles are alike or similar to each other when their sides are proportionate and have the same angles.
The only way they are both alike as if they a equilateral.
They are both polygons
they both have right angles , they're both quadrangles, they both have parallel lines, and they both have straight lines
They are alike inasmuch that a rectangle can be split into two right angle triangles
Thy both have three angles.
All their sides are the same length
They both have 3 sides and 3 interior angles that add up to 180 degrees.
Well, a hexagon is made of six equilateral triangles.
Because they are both triangles and they are both 3 dimensional!