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A wire when bent in the form of a square encloses an area of 484 m2. Find the largest area enclosed by the same wire when bent to from: i. An equilateral triangle. ii. A rectangle of length 16 m.

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Question

A wire when bent in the form of a square encloses an area of 484 m2. Find the largest area enclosed by the same wire when bent to from:

  1. An equilateral triangle.
  2. A rectangle of length 16 m.
Sum
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Solution

The area of the square is 484.

Let a be the length of each side of the square.

Now

a2 = 484 

a = 22 m

Hence, the length of the wire is = 4 × 22 = 88 m.

(i) Now, this 88 m wire is bent in the form of an equilateral triangle.

Side of the triangle = `88/3`

= 29.3 m

Area of the triangle = `sqrt3/4` × (Side)2

= `sqrt3/4` × (29.3)2

= 372.58 m2

(ii) Let x be the breadth of the rectangle.

Now,

2(l + b) = 88

16 + x = 44

x = 28 m

Hence, area = 16 × 28 = 448 m2.

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Chapter 19: Area and Perimeter of Plane Figures - Exercise 20 (B) [Page 256]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 19 Area and Perimeter of Plane Figures
Exercise 20 (B) | Q 26 | Page 256

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