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

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Herons Formula and its components

Herons Formula

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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