Quadri means four. Lateral means sides. A quadrilateral has four sides.
Because a quad has 4 wheels and a quadrilateral has 4 sides!
For the same reason that a cat is an animal but an animal is not always a cat.Because a trapezoid is a special kind of quadrilateral. A quadrilateral is anything with four sides.A trapezoid has four...
four sides and a closed shape
Four straight lines in a plane, meeting in pairs at four vertices.