Page 241 - ICSE Math 7

9. The given figure shows a rectangle. Find the area of the shaded region.

A 18 cm B
3 cm

F
10 cm
7 cm
B
D E 14 cm C

10. Find the area of the quadrilateral ABCD, in which 3 cm
BM AC, DN AC, AC = 20 cm, BM = 3 cm and N 20 cm
DN = 2 cm. A M C

2 cm
11. Find the area of the shaded portion of the given rectangle.
D
8 cm

4 cm
6 cm

6 cm

5 cm 9 cm

Circle

The length of the boundary of a circle is its circumference.
22 r
Circumference of a circle = 2pr (where approximate value of p is 7 or 3.14)

Area of a Circle
22
Area of a circle of radius r = pr 2 (where approximate value of p is 7 ) Maths Info
Area of a circular Ring = Area of outer circle – Area of inner circle A circular ring is a plane figure
2
2
2
2
= pR – pr = p(R – r ) bounded by the circumference
of two concentric circles of
Example 12: Find the circumference and area of a circle having radius different radii.
35 cm. (Take p = 22 )
7
22
Solution: Circumference of a circle = 2pr = 2 × × 35 cm = 220 cm
7 O r
22
Area of a circle = 2pr = × 35 cm × 35 cm = 3,850 cm 2
7 R

Example 13: If the circumference of a circular sheet is 132 cm, find its radius and area.
22
(Take p = )
7

227