Isosceles Triangle Calculator


What is an Isosceles Triangle Calculator?

An Isosceles Triangle Calculator is an online tool which calculates the area and perimeter of an isosceles triangle, when the base and the equal side is given. This calculator helps you to calculate faster and displays the result within a few seconds.

How to Use the Isosceles Triangle Calculator?

Follow the steps given below to use the calculator:

  • Step 1: Enter the base and the equal side of the isosceles triangle in the respective input boxes.
  • Step 2: Click on "Calculate" to find the area and the perimeter of the isosceles triangle.
  • Step 3: Click on "Reset" to clear the fields and enter the new values.

What is an Isosceles Triangle?

A triangle with two sides of equal length is an isosceles triangle. The area of an isosceles triangle is calculated using the formula:

Area = (1/2) × b × h

where b = base of the triangle; h = height of the triangle

The perimeter of an isosceles triangle is calculated with the help of the following formula:

Perimeter = 2a + b

where a = length of the equal side; b = base

The isosceles triangle calculator in this page uses the same formulas to calculate the area and perimeter of an isosceles triangle.

Solved Example :

Find the area and perimeter of an isosceles triangle whose height is 4 units, base is 6 units and one of its equal sides is 5 units.

Solution :

Height of the isosceles triangle (h)  = 4 units; Base of the isosceles triangle (b) = 6 units

Area = (1/2) × b × h

= (1/2) × 6 × 4 

= 12 square units.

Now, let us calculate the perimeter with the given dimensions.

Length of the equal side (a) = 5 units; Base of the triangle (b) = 6 units

Perimeter = 2a + b units

= (2 × 5) + 6

= 10 + 6

= 16 units.

 ∴  Area of the isoceles triangle = 12 square units.
     Perimeter of the isoceles triangle = 16 units.

Now use the calculator to find the area and perimeter for the following isosceles triangles with:

  •  Base = 12 units; one of the equal sides = 10 units
  •  Base = 8 units; one of the equal sides = 4 units

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