What is an irregular triangle?

What is an irregular triangle?

• A. Isosceles; Two sides same length.
• B. Scalene. NO sides and NO angles are the same measure.
• C. Equilateral; Three sides same length.
• D. Right triangle; One angle 90 degrees.

Answer: (B)

An irregular triangle means a triangle that isn’t regular—there aren’t any equal sides or equal angles by the usual definitions. When all three side lengths are different, you get what geometry calls a scalene triangle, and in a scalene triangle the three interior angles are all different as well. So there are no equal sides and no equal angles. That’s why this describes an irregular triangle. To connect the other terms: an isosceles triangle has two equal sides, equilateral has three equal sides, and a right triangle is defined by having a 90-degree angle—these properties can occur with or without irregularity, but irregularity specifically points to all sides (and thus all angles) being different.

An irregular triangle means a triangle that isn’t regular—there aren’t any equal sides or equal angles by the usual definitions. When all three side lengths are different, you get what geometry calls a scalene triangle, and in a scalene triangle the three interior angles are all different as well. So there are no equal sides and no equal angles. That’s why this describes an irregular triangle.

To connect the other terms: an isosceles triangle has two equal sides, equilateral has three equal sides, and a right triangle is defined by having a 90-degree angle—these properties can occur with or without irregularity, but irregularity specifically points to all sides (and thus all angles) being different.