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The sides of a triangle are 56 cm, 60 cm and 52 cm long. Then the area of the triangle is ______. - Mathematics

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Question

The sides of a triangle are 56 cm, 60 cm and 52 cm long. Then the area of the triangle is ______.

Options

  • 1322 cm2 

  • 1311 cm2 

  • 1344 cm2 

  • 1392 cm

MCQ
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Solution

The sides of a triangle are 56 cm, 60 cm and 52 cm long. Then the area of the triangle is 1344 cm2.

Explanation:

The sides of a triangle area = 56 cm, b = 60 cm and c = 52 cm.

So, semi-perimeter of a triangle will be:

`s = (a + b + c)/2`

= `(56 + 60 + 52)/2`

= `168/2`

= 84 cm

Area of the triangle = `sqrt(s(s - a)(s- b)(s - c))`  ...[By heron’s formula]

= `sqrt(84(84 - 56)(84 - 60)(84 - 52))`

= `sqrt(84 xx 28 xx 24 xx 32)`

= `sqrt(4 xx 7 xx 3 xx 4 xx 7 xx 4 xx 2 xx 3 xx 4 xx 4 xx 2)`

= `sqrt(4^6 xx 7^2 xx 3^2)`

= 43 × 7 × 3

= 1344 cm2 

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Chapter 12: Heron's Formula - Exercise 12.1 [Page 114]

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NCERT Exemplar Mathematics [English] Class 9
Chapter 12 Heron's Formula
Exercise 12.1 | Q 3. | Page 114

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