How to classify triangles by sides and angles


Angles


  • An acute triangle has to have three acute angles. An acute angle is less than 90˚.
acutetriangle.jpg
  • An obtuse triangle has at least one angle larger than 90˚. An obtuse angle is less than 180˚ and more than 90˚.
obtusetriangle.jpg
  • Lastly a right triangle has one 90˚ angle.
righttriangle.jpg


Now, let’s talk about sides.

  • The first one that you need to know about is isosceles. An isosceles triangle is a triangle that has two sides that are the same length and one that is not the same length as the other two sides.
isosceles.jpg

  • The second one that you need to know is an equilateral triangle and an equilateral triangle is when all three of the sides are the same.
equilateral.jpg

  • Then the last one that you need to know is a scalene triangle and a scalene triangle is a triangle when none of the sides are the same.
scalene.jpg