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Length of the fence of a trapezium shaped field ABCD is 120 m. If BC = 48 m, CD = 17 m and AD = 40 m, find the area of this field. Side AB is perpendicular to the parallel sides AD and BC. - Mathematics

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Question

Length of the fence of a trapezium shaped field ABCD is 120 m. If BC = 48 m, CD = 17 m and AD = 40 m, find the area of this field. Side AB is perpendicular to the parallel sides AD and BC.

Sum
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Solution

AB = DE

EC = BC − BE

EC = (48 − 40) m

EC = 8 m

In Δ DEC,

(DE)2 + (EC)2 = (D C)2

(DE)2 + (8)2 = (17)2

(DE)2 = (17)2 − (8)2

DE = 289 − 64

DE = 225 m2

DE = `sqrt225` m

 DE = 15 m

AB = 15 m

Area of trapezium, ABCD

`= 1/2` × (sum of parallel sides) × Height

`= 1/2` × (AD + BC) × AB

`1/2` × (40 + 48) ×15

= 660m2

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Chapter 9: Mensuration - EXERCISE 9.1 [Page 106]

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NCERT Mathematics [English] Class 8
Chapter 9 Mensuration
EXERCISE 9.1 | Q 3. | Page 106

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