Chapter 20. Perimeters and Area of Plane Figures
Chapter 20. Perimeters and Area of Plane Figures
Chapter 20. Perimeters and Area of Plane Figures
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
MODULE - 4<br />
Mensuration<br />
Notes<br />
<strong>Perimeters</strong> <strong>and</strong> <strong>Area</strong>s <strong>of</strong> <strong>Plane</strong> <strong>Figures</strong><br />
• <strong>Area</strong>s <strong>of</strong> many rectilinear figures can be found by dividing them into known figures<br />
such as squares, rectangles, triangles <strong>and</strong> so on.<br />
• <strong>Area</strong>s <strong>of</strong> various combinations <strong>of</strong> figures <strong>and</strong> designs involving circles can also be<br />
found by using different known formulas.<br />
TERMINAL EXERCISE<br />
1. The side <strong>of</strong> a square park is 37.5 m. Find its area.<br />
2. The perimeter <strong>of</strong> a square is 480 cm. Find its area.<br />
3. Find the time taken by a person in walking along the boundary <strong>of</strong> a square field <strong>of</strong> area<br />
40 000 m 2 at a speed <strong>of</strong> 4 km/h.<br />
4. Length <strong>of</strong> a room is three times its breadth. If its breadth is 4.5 m, find the area <strong>of</strong> the<br />
floor.<br />
5. The length <strong>and</strong> breadth <strong>of</strong> a rectangle are in the ratio <strong>of</strong> 5 : 2 <strong>and</strong> its perimeter is 980<br />
cm. Find the area <strong>of</strong> the rectangle.<br />
6. Find the area <strong>of</strong> each <strong>of</strong> the following parallelograms:<br />
(i) one side is 25 cm <strong>and</strong> corresponding altitude is 12 cm<br />
(ii) Two adjacent sides are 13 cm <strong>and</strong> 14 cm <strong>and</strong> one diagonal is 15 cm.<br />
7. The area <strong>of</strong> a rectangular field is 27000 m 2 <strong>and</strong> its length <strong>and</strong> breadth are in the ratio<br />
6:5. Find the cost <strong>of</strong> fencing the field by four rounds <strong>of</strong> barbed wire at the rate <strong>of</strong> ` 7<br />
per 10 metre.<br />
8. Find the area <strong>of</strong> each <strong>of</strong> the following trapeziums:<br />
S. No. Lengths <strong>of</strong> parellel sides Distance between the parallel sides<br />
(i) 30 cm <strong>and</strong> 20 cm 15 cm<br />
(ii) 15.5 cm <strong>and</strong> 10.5 cm 7.5 cm<br />
(iii) 15 cm <strong>and</strong> 45 cm 14.6 cm<br />
(iv) 40 cm <strong>and</strong> 22 cm 12 cm<br />
9. Find the area <strong>of</strong> a plot which is in the shape <strong>of</strong> a quadrilateral, one <strong>of</strong> whose diagonals<br />
is 20 m <strong>and</strong> lengths <strong>of</strong> the perpendiculars from the opposite corners on it are <strong>of</strong> lengths<br />
12 m <strong>and</strong> 18 m respectively.<br />
10. Find the area <strong>of</strong> a field in the shape <strong>of</strong> a trapezium whose parallel sides are <strong>of</strong> lengths<br />
48 m <strong>and</strong> 160 m <strong>and</strong> non-parallel sides <strong>of</strong> lengths 50 m <strong>and</strong> 78 m.<br />
474<br />
Mathematics Secondary Course
Change language