# Heron’s Formula

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## 12 Heron’s Formula

#### HERON’S FORMULA

Heron’s formula to find area of triangle:

If length of three sides of triangle are a, b, c then,

The semiperimetre

And the area of

Example:

Find area of triangular plot as in figure.

Here sides of triangle are units

units, units, units

Area

sq units

Application of Heron’s formula:

Area of irregular polygon:

We can apply heron’s formula to find area of irregular polygon by dividing it into number of triangles.

Example: Find area of polygon $\text{PQRST}$.

Area of polygon

For $\Delta \text{PQT}$,

units

Area

sq.Units

For $\Delta \text{TQS}$,

units

Area

sq. units

For $\Delta \text{SQT}$,

units

Area

sq. units

Area of polygon =

sq. units.