Heron’s Formula Class 9 Notes Maths - Chapter 12

Chapter: 12

What Are Heron’s Formula ?


Area of plane figure is a measure of region enclosed by it.

Area Of Triangle

  • By Altitude : Area = (1/2)(b × h) b = base, h = altitude
  • By Heron’s Formula : Area =√s(s-a)(s-b)(s-c)

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

(s = semiperimeter) and a, b, c are the sides of the triangle.

Area Of Isosceles Triangle

Area = (b/4) √4a2-b2

Where, b = base

a = equal sides

Area Of Equilateral Triangle

Area =(√3/4)×a2

Where, a = equal sides

Altitude (Height) Of Equilateral Triangle

Altitude (h) =(√3/2)×a

Where, a = side