Triangular and Quadrangular

adjective

• Having three angles; forming or shaped like a triangle.
  • usage: "a triangular figure"; "a triangular pyrimid has a triangle for a base"
• Having three sides.
  • usage: "a trilateral figure"
  • synonyms: trilateral, three-sided

• (a.) Oblong or elongated, and having three lateral angles; as, a triangular seed, leaf or stem.
• (a.) Having three angles; having the form of a triangle.

adjective

• Of or relating to or shaped like a quadrangle. .

(a.) Having four angles, and consequently four sides; tetragonal.