Learn Class 9 Math - Quadrilaterals

The term quadrilateral refers to a figure enclosed by the four sides that are not equal. And the sum of all angles of a quadrilateral is always equal to 360 degrees.

Types of a Quadrilateral

1. Parallelogram

  • It is an enclosed figure with four sides.
  • The parallelogram is a figure whose opposite sides are equal.

2. Rectangle

  • It is an enclosed figure with four sides.
  • The rectangle is a figure whose opposite sides are equal.
  • Every angle of the rectangle is always equal to 90 degrees.

3. Square

  • The square is an enclosed figure with four equal sides.
  • Every angle of the rectangle is always equal to 90 degrees.

4. Rhombus

  • The rhombus is a parallelogram whose all sides are equal.

5. Kite

  • It is a figure whose adjacent angles are equal.

Problem

If ABFE is a trapezium, then prove that C is the midpoint of BF and AB is parallel to EF, whereas D is the midpoint of AE. And EF is parallel to DC.

Solution:

BE cut DC at a point, i.e., G.

Now in

With the help of the midpoint theorem, G is known as the midpoint of EB.

In the ∆, G is the midpoint of BE and GC is parallel to EF.

With the midpoint theorem, C becomes the midpoint of BF.

It is proved that c is the midpoint of the side BF.