Classify triangles

Key notes:

Classification of Triangles

  1. Based on Sides:
    • Equilateral Triangle: All three sides are equal in length. Each angle measures 60 degrees.
    • Isosceles Triangle: Two sides are equal in length. The angles opposite the equal sides are also equal.
    • Scalene Triangle: All three sides are of different lengths. All angles are different.
  2. Based on Angles:
    • Acute Triangle: All three angles are less than 90 degrees.
    • Right Triangle: One angle measures exactly 90 degrees. The side opposite the right angle is the longest and is called the hypotenuse.
    • Obtuse Triangle: One angle is greater than 90 degrees.
  3. Visual Representation:
    • Use diagrams to show examples of each type of triangle based on sides and angles.
  4. Properties:
    • The sum of the interior angles in any triangle is always 180 degrees.
    • In any triangle, the longest side is opposite the largest angle.

Learn with an example

➡️ What kind of triangle is this?

  • acute
  • right
  • obtuse

This triangle is an acute triangle. All 3 angles are less than 90°.

➡️ A triangle has angle measurements of 11°, 79° and 90°. What kind of triangle is it?

  • acute
  • right
  • obtuse

This triangle is a right triangle. The 90° angle is a right angle.

➡️ A triangle has angle measurements of 7°, 50° and 123°. What kind of triangle is it?

  • acute
  • right
  • obtuse

This triangle is an obtuse triangle. The 123° angle is greater than 90°.

Let’s practice!🖊️