# Finding area of triangle in JavaScript using Heron’s formula

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

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We are given the lengths of three sides of a triangle and we are required to write a function that returns the area of the triangle using the length of its sides.

## Heron's formula

We can calculate the area of a triangle if we know the lengths of all three sides, using Heron's formula −

Step 1 − Calculate "s" (half of the triangles perimeter) −

s = (a+b+c) / 2

Step 2 − Then calculate the Area using Herons formula −

A = sqrt( s(s-a)(s-b)(s-c) )

## Example

So, Let’s write the code for this function −

const sides = [12, 4, 9];
const areaOfTriangle = sides => {
const [a, b, c] = sides;
const sp = (a + b + c) / 2;
const aDifference = sp - a;
const bDiffernece = sp - b;
const cDifference = sp - c;
const area = Math.sqrt(sp * aDifference * bDiffernece * cDifference);
return area;
};
console.log(areaOfTriangle(sides));

## Output

The output in the console: −

13.635890143294644