# NCERT Class 9 Solutions: Heron's Formula (Chapter 12) Exercise 12.1 Part 2

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Q-5 Sides of a triangle are in the ratio of and its perimeter is . Find its area.Solution:

Ratio of the sides of the triangle

Let the common ratio be then sides are

Perimeter of the triangle

()

Sides of triangle are,

()

()

()

Semi perimeter of triangle(s)

Using heron's formula, area of the triangle

Q-6 An isosceles triangle has perimeter 30 cm and each of the equal sides is 12 cm. Find the area of the triangle.Solution:

Length of the equal sides

Perimeter of the triangle

Length of the third side

Semi perimeter of the triangle(s)

Using heron's formula, area of the triangle