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How to Classify Triangles as Scalene, Isosceles or Right

The classification of triangles lies with the three sides that construct them and the three interior angles that the sides create. Three different classes of triangles include the scalene, isosceles and right triangle. A scalene triangle is a mismatched triangle, an isosceles one has at least one pair of matching sides and angles, and a right triangle has one defining angle of extreme trigonometric importance. By measuring and comparing sides and angles, you can prove what type of triangle it is.

Ruler
Protractor

Instructions

- 1
  Measure each of the triangle's sides with your ruler. If none of the side's measure the same length, the triangle is a scalene triangle.
- 2
  Measure each of the sides with your ruler. If at least two of the sides have the same measurement, the triangle is an isosceles triangle. Note that if all three of the sides have the same measurement, then the triangle is a special type of isosceles triangle termed an equilateral triangle.
- 3
  Measure each interior angle with your protractor. If none of the angles have the same measurement, the triangle is a scalene triangle.
- 4
  Measure each interior angle with your protractor. If at least two of the angles have the same measurement, the triangle is an isosceles triangle. Note that if all three angles have the same measurement, then the triangle is equilateral.
- 5
  Measure each of the triangle's angles. If one of the angles measures 90 degrees, the triangle possesses a right angle and is a right triangle. Note that a triangle can only have one right angle, since all three angles together equal 180 degrees.

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