JavaScript Basic: Find The Area Of A Triangle Where Lengths Of The ...

JavaScript: Find the area of a triangle where lengths of the three of its sides are 5, 6, 7 Last update on June 30 2025 13:10:38 (UTC/GMT +8 hours)

JavaScript Basic: Exercise-4 with Solution

Calculate Area of Triangle (Sides: 5, 6, 7)

Write a JavaScript program to find the area of a triangle where three sides are 5, 6, 7.

This JavaScript program calculates the area of a triangle with sides of lengths 5, 6, and 7 using Heron's formula. It first computes the semi-perimeter (s) of the triangle, then uses it to find the area, which is logged to the console.

Sample Solution:

JavaScript Code:

// Define the lengths of the three sides of a triangle var side1 = 5; var side2 = 6; var side3 = 7; // Calculate the semi-perimeter of the triangle var s = (side1 + side2 + side3) / 2; // Use Heron's formula to calculate the area of the triangle var area = Math.sqrt(s * ((s - side1) * (s - side2) * (s - side3))); // Log the calculated area to the console console.log(area);

Output:

14.696938456699069

Live Demo:

See the Pen JavaScript: Area of Triangle - basic-ex-4 by w3resource (@w3resource) on CodePen.

Explanation: Calculate the area of a triangle of three given sides : In geometry, Heron's formula named after Hero of Alexandria, gives the area of a triangle by requiring no arbitrary choice of side as base or vertex as origin, contrary to other formulas for the area of a triangle, such as half the base times the height or half the norm of a cross product of two sides.

The Math.sqrt() function is used to get the square root of a number. If the value of the number is negative, Math.sqrt() returns NaN.

ES6 Version:

// Declare constants for the lengths of the three sides of a triangle const side1 = 5; const side2 = 6; const side3 = 7; // Calculate the semi-perimeter of the triangle const perimeter = (side1 + side2 + side3) / 2; // Use Heron's formula to calculate the area of the triangle const area = Math.sqrt(perimeter * ((perimeter - side1) * (perimeter - side2) * (perimeter - side3))); // Log the calculated area to the console console.log(area);

For more Practice: Solve these Related Problems:

• Write a JavaScript program to calculate the area of a triangle using Heron’s formula with sides provided by the user.
• Write a JavaScript program that validates the triangle side lengths before calculating the area to ensure they form a valid triangle.
• Write a JavaScript program that computes the area of a triangle given an array of side lengths, checking for the triangle inequality.

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