Measure each side of the triangle using a ruler. Ensure that the same unit of measurement is used for each side.
Record each respective measurement.
Identify the classification of the triangle based on the recorded measurements. There are essentially three classifications of triangles based on the length of the sides. An equilateral classification identifies triangles with all three sides equal in measure. An isosceles classification results from a triangle having only two sides with equivalent measurements. A triangle with different lengths for all three sides is classified as a scalene triangle.
Measure the angle of each of the three corners using a protractor.
Record each angle measurement at the respective corners.
Identify the classification based on the recorded angles. A right triangle classification is given for a triangle that has a measurement of 90 degrees for one of the angles. An obtuse classification identifies a triangle with an angle greater than 90 degrees but less than 180 degrees, as the sum of the angles within all types of triangles must always equal 180 degrees. Triangles with all three angles measuring less than 90 degrees are classified as acute triangles. Those with all three angles equal are classified as equiangular. An equiangular triangle will have all angles equal to 60 degrees.