Perimeter and Area NCERT In Text Questions

Question 1: Each of the following rectangles of length 6 cm and breadth 4 cm is composed of congruent polygons. Find the area of each polygon.

Solution: Figure A has 6 congruent polygons.

Hence, area of each polygon = Area of rectangle ÷ 6

Area of rectangle = length × breadth

`= 6 xx 4 = 24` sq cm

Hence, area of each polygon of A `= 24 ÷ 6 = 4` cm²

Figure B has 4 congruent polygons.

Hence, area of each polygon = Area of rectangle ÷ 4

`= 24 ÷ 4 = 6` sq cm

Figure C has 2 congruent polygons.

Hence, are of each polygon = Area of rectangle ÷ 2

`= 24 ÷ 2 = 12` sq cm

Figure D has 2 congruent polygons.

Hence, are of each polygon = Area of rectangle ÷ 2

`= 24 ÷ 2 = 12` sq cm

Figure E has 8 congruent polygons.

Hence, area of each polygon = Area of rectangle ÷ 8

`= 24 ÷ 8 = 3` sq cm

Question 2: Find the area of following parallelograms:

(i) Given, Base = 8cm, Height = 3.5 cm

Therefore, Area = Base × Height

`= 8 xx 3.5c = 28.0` cm²

(ii) Given, Base = 8cm, Height = 2.5 cm

Therefore, Area = Base `xx` Height

`= 8xx 2.5= 20.0` cm²

(iii) In a parallelogram ABCD, AB = 7.2cm and the perpendicular from C on AB is 4.5cm.

Area of parallelogram ABCD = Base `xx` Height

`= 7.2 xx 4.5 = 32.40` cm²