# Sides of a triangle are in the ratio of 12:17:25 and its perimeter is 540cm. Find its area.

**Solution:**

Given: Ratio of sides of the triangle and its perimeter.

By using Heron’s formula, we can calculate the area of a triangle.

Heron's formula for the area of a triangle is: Area = √s(s - a)(s - b)(s - c)

Where a, b, and c are the sides of the triangle, and s = Semi-perimeter = Half the perimeter of the triangle

Since the ratios of the sides of the triangle are given as 12:17:25

So, we can assume the length of the sides of the triangle as 12x cm, 17x cm, and 25x cm.

So the perimeter of the triangle will be

Perimeter = 12x + 17x + 25x

12x + 17x + 25x = 540 (given)

54x = 540

x = 540/54

x = 10 cm

Therefore, the sides of the triangle:

12x = 12 × 10 = 120 cm, 17x = 17 × 10 = 170 cm, 25x = 25 × 10 = 250 cm

a = 120cm, b = 170 cm, c = 250 cm

Semi-perimeter(s) = 540/2 = 270 cm

By using Heron’s formula,

Area of a triangle = √s(s - a)(s - b)(s - c)

= √270(270 - 120)(270 - 170)(270 - 250)

= √270 × 150 × 100 × 20

= √81000000

= 9000 cm^{2}

Area of the triangle = 9000 cm^{2}.

**☛ Check: **NCERT Solutions for Class 9 Maths Chapter 12

**Video Solution:**

## Sides of a triangle are in the ratio of 12:17:25 and its perimeter is 540cm. Find its area.

Class 9 Maths NCERT Solutions Chapter 12 Exercise 12.1 Question 5

**Summary:**

It is given that sides of a triangle are in the ratio of 12:17:25 and its perimeter is 540 cm. We have found that its area is 9000 cm^{2}.

**☛ Related Questions:**

- The triangular side walls of a flyover have been used for advertisements. The sides of the walls are 122 m, 22 m, and 120 m (see Fig. 12.9). The advertisements yield an earning of ₹ 5000 per m2 per year. A company hired one of its walls for 3 months. How much rent did it pay?
- There is a slide in a park. One of its side walls has been painted in some colour with a message “KEEP THE PARK GREEN AND CLEAN” (see Fig. 12.10). If the sides of the wall are 15 m, 11 m and 6 m, find the area painted in colour.
- Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm.
- An isosceles triangle has perimeter 30 cm and each of the equal sides is 12 cm. Find the area of the triangle.

visual curriculum