Notes of chapter: Quadrilaterals are presented below. Indepth notes along with worksheets and NCERT Solutions.

(1) Plane surface-

A surface which has no thickness and extends in all directions is called plane surface.

Eg :- Paper

(2)Plane curve-

A plane curve is a curve that can be obtained by joining a number of points and without retracing any portion of the drawing other than single points.

Eg:- Circle

(3)Diagonal-

A diagonal is a line segment connecting two non- consecutive vertices of a polygon.

Eg:-

(i)      (4) Interior of a closed curve-

The interior of a closed curve is an area inside the boundary of closed curve.

Eg:- (5) Exterior of a closed curve

The exterior of a closed curve is an area outside the boundary of closed curve.

Eg:- (6)Polygons-

Polygons are closed figures with straight line segments. These segments are called edges or sides. Their meeting points are called vertices.

Eg:- Triangle, square, parallelogram etc.

Polygons

Quadrilateral is a polygon that has four sides and four vertices.

Eg:- Rectangle, square, kite etc.

All have four sides and four vertices.

(8) The sum of angles of a quadrilateral  (i) Trapezium

(a) It has four sides.

(b) It has a pair of parallel sides.

Eg:-  (ii)Kite-

(a) Kite has four sides.

(b) It has two distinct consecutive pairs of sides of equal length.

(c) Angles are equal between unequal straight lines.

Eg:-  (iii) Parallelogram-

(a) It has four sides.

(b)Its opposite sides are parallel and equal in length.

(c)The opposite angles of a parallelogram are of equal measure.

(d) The consecutive angles in a parallelogram are supplementary.

(e) The diagonals of a parallelogram bisect each other at the point of intersection.

Eg:-  (iv) Rhombus

(a) It is a quadrilateral with four sides of equal length.

(b) The diagonals of a rhombus are perpendicular bisectors of one another.

(c)Rhombus is a parallelogram but also has properties of kite.

Eg:-  (v) Rectangle

(a) It has four sides. Opposite sides are equal and parallel.

(b) Each angle of rectangle is right angle.

(c) Diagonals of the rectangle bisect each other and are equal in length.

Eg:-  (vi) Square

(a) It has all the properties of rectangle.

(b) The diagonals of a square are perpendicular bisectors of each other.

Eg:-      Helping Topics

NCERT Solutions Class 8

NCERT Solutions Class 9

Worksheet Class 8

Worksheet Class 9