LESSON: Classifying Triangles

Objectives/Vocab

Objectives

  • Classify triangles by angles.
  • Classify triangles by sides.
  • Draw specified triangles using a ruler and a protractor.
  • Find unknown angle measures in given triangles.

Vocabulary

Triangle
a three sided figure with three angles. The prefix “tri”means three.
Acute Triangle
all three angles are less than 90 degrees.
Right Triangle
One angle is equal to 90 degrees and the other two are acute angles.
Obtuse Triangle
One angle is greater than 90 degrees and the other two are acute angles.
Equiangular Triangle
all three angles are equal
Scalene Triangle
all three side lengths are different
Isosceles Triangle
two sides lengths are the same and one is different
Equilateral Triangle
all three side lengths are the same
Protractor
A tool used to measure angles
Interior angles
the angles inside a figure