There are 3 ways to describe a triangle when you are referring to the sides of the shape. The key thing to know is that a triangle is a polygon with 3 sides. Once you remember that a triangle is a shape with 3 sides and 3 angles that add up to 180; you will note that none of the sides will be equal, 2 of the sides will be equal, or all 3 of the sides will be equal.