* A closed figure formed by three line segments is called a triangle.
* A triangle has 3 sides, 3 angles and 3 vertices.
* Based on the sides of triangles, we can classify triangles into 3 types as scalene triangle, isosceles triangle and equilateral triangle.
* Based on the angles of triangles, we can classify triangles into 3 types as acute angled triangle, right angled triangle and obtuse angled triangle.
* In a triangle, the sum of any two sides is greater than the third side. This is known as Triangle Inequality property.
* Sum of three angles of a triangle is 180°.
* Parallel and Perperndicular lines can easily be drawn using set squares.
* The distance between a set of parallel lines always remains the same.