Class IX Mathematics

Chapter 10: Heron's Formula

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Key Formulas & Equations

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Semi-perimeter

s = \frac{a+b+c}{2}

Half the perimeter of a triangle.

Heron's Formula

A = \sqrt{s(s-a)(s-b)(s-c)}

Calculates triangle area using semi-perimeter s and sides a, b, c.

Related Formulas from Adjacent Chapters

Volume of Sphere

V = \frac{4}{3}\pi r^3

[From Surface Areas and Volumes] Volume capacity of sphere.

Surface Area of Sphere

A = 4\pi r^2

[From Surface Areas and Volumes] Total outer surface area of sphere.

Volume of Cone

V = \frac{1}{3}\pi r^2 h

[From Surface Areas and Volumes] Volume of right circular cone.