Class 6 – MATHEMATICS
    About Lesson

    Basic geometrical ideas(2D)

    Triangle 

    • A triangle is simple closed figure made up of three line segments.

    • There are three angles in a triangle.

    • The point of intersection of two adjacent sides of a triangle is called a vertex. There are 3 vertices in a triangle.

    • A line segment joining a vertex to the mid- point of the side opposite to the vertex is called a median of the triangle. 

    • An altitude of a triangle is the perpendicular drawn from a vertex to the opposite side( produce if necessary).

    Quadrilateral

    • The figure made up of the four line segments is called the quadrilateral.

    • There are four angles in a quadrilateral.

    • A line segment joining two non-consecutive vertices is called a diagonal.

    • Two sides of a quadrilateral are said to be the adjacent sides of the quadrilateral, if they have a common end point.

    • Two sides of a quadrilateral are said to be opposite sides of the quadrilateral, if they are not adjacent sides.