Page 147 - Maths Skills - 7

Perimeter and Area 145

5. Find the area of a circle whose diameter is 7.7 cm.

6. In Fig., the circular field is surrounded by a flower garden of 10 m width. If the
radius of the circular field is 65 m, then find the area of the flower garden.
7. The area enclosed by two concentric circles is 330 sq cm. If the radius of the smaller
circle is 8 cm, then find the radius of the bigger circle.
8. The cost of turfing the circular field at the rate of ` 9 per sq m is ` 5544. Find the
diameter of the field.

9. In Fig., ABCD is a square. If a circle of radius 14 cm is inscribed in it, then find the
area of the shaded region.

10. The diameter of a circular park is 80 metres. A 4 m wide road runs outside around 80 m
it. Find the cost of constructing the road at ` 10 per sq metre.

11. The shape of a park is in the form of a rectangle of length 18 cm and
breadth 14 cm. If a circle is inscribed in it, then find the area of the shaded
portion as shown in Fig.

60°

12. Find the area of the shaded portion of Fig. [Hint: Consider 3 = 1.732]

60° 60°

ASSESSMENT TIME

COMPETENCY BASED QUESTIONS 3. A wheel makes 1000 revolution in covering a
distance of 66 km. The radius of the wheel is:
A. Multiple-Choice Questions (i) 21 m (ii) 66 m
1. If the area of a triangle with base ‘b’ is equal to
the area of a square ‘s’ which is on the same base (iii) 10.5 m (iv) none of these
then the altitude of the triangle is: 4. One side of a rhombus is 10 cm and one of its
b diagonal is 16 cm. The area of the rhombus is:
(i) (ii) 2b
2 (i) 96 cm (ii) 192 cm 2
2
(iii) b (iv) 2b (iii) 52 cm (iv) 160 cm 2
2
2. The circumference of two concentric circles are 5. The area of a parallelogram is 620 cm and one
2
150 cm and 106 cm respectively. The difference of its sides is 20 cm. The corresponding altitude
between their radii is: will be:
(i) 3.5 cm (ii) 44 cm (i) 16 cm (ii) 20 cm

(iii) 7 cm (iv) 16 cm (iii) 31 cm (iv) 62 cm