Following are the important properties of triangles:

1. The sum of angles of a triangle is 180°.
2. Isosceles triangles have two sides that are equal.
3. The angles opposite the equal sides in an isosceles triangle are equal.
4. All sides of an equilateral triangle are equal.
5. All angles of an equilateral triangle are equal. Each angle is 60°.
6. A right-angled triangle has one angle that is equal to 90°.
7. The sum of the other two angles of a right-angled triangle is 90°.