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Find the area of triangle with following sides. [All measures are in cm.] 17, 25, 28 - Mathematics

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Question

Find the area of triangle with following sides. [All measures are in cm.]

17, 25, 28

Sum
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Solution

Given:

Sides of the triangle are 17 cm, 25 cm, 28 cm.

Step 1: Calculate the semi-perimeter (s)

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

= `(17 + 25 + 28)/2`

= `70/2`

= 35 cm

Step 2: Use Heron’s formula to find the area (A)

`A = sqrt(s(s - a)(s - b)(s - c))`

= `sqrt(35(35 - 17)(35 - 25)(35 - 28))`

= `sqrt(35 xx 18 xx 10 xx 7)`

Calculate inside the square root:

35 × 18 = 630

630 × 10 = 6300

6300 × 7 = 44100

Step 3: Calculate the square root

`A = sqrt(44100)`

A = 210 cm2

The area of the triangle with sides 17 cm, 25 cm and 28 cm is 210 cm2.

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Chapter 17: Mensuration - EXERCISE 17A [Page 201]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 17 Mensuration
EXERCISE 17A | Q 1. (ii) | Page 201
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