Triangular and Rectangular

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

• Having four right angles.
  • usage: "a rectangular figure twice as long as it is wide"
• Having a set of mutually perpendicular axes; meeting at right angles.
  • usage: "wind and sea may displace the ship's center of gravity along three orthogonal axes"; "a rectangular Cartesian coordinate system"
  • synonyms: orthogonal

(a.) Right-angled; having one or more angles of ninety degrees.