Isosceles Triangle Calculator

The solution of a particular type of triangle needs specific formulas according to the measures you are looking to find. For example, the area measurement for an Isosceles triangle will be different from the area measurement of an equilateral triangle. Similarly, it goes with other measurements like perimeter.

Sometimes, you may have to solve problems related to an Isosceles triangle and want to calculate its different measurements. It will be a long process if you do it manually as well as you may get low accuracy. To deal with such problems, the best way is to use the Isosceles triangle calculator. This tool has been designed to give you detailed information according to your required input data. Keep reading to learn the way to use this maths calculator.

What is Isosceles Triangle?

It is a particular type of triangle that has two sides of equal measure while the third side will have a different length. Similarly, the measures of two angles will be the same in the Isosceles triangle while the third angle will be of different measure.

Simply, an Isosceles triangle is a specific type of triangle with two equal sides and two equal angles. In this triangle, some terms are used to show its sides. The equal sides of an Isosceles triangle are called its legs while the third side is called the base. Similarly, the angle between two legs of this triangle is called the vertex angle while the angle between the base and a leg is called the base angle.

Isosceles Triangle Formula for area and perimeter

Like other types of triangles, the Isosceles triangle also has specific formulas to find its area and perimeter. Here we are going to show those formulas that you have to utilize for measuring these parameters.

Area of an Isosceles Triangle = b/4 ✖ √4a2 - b2	


  • “b” represents the base of the Isosceles Triangle
  • “a” represents the leg of the Isosceles Triangle

Similarly, we can find the Perimeter of the Isosceles Triangle using the following formula:

Perimeter of an Isosceles Triangle = a + b + c	

We can also write it as

Perimeter = 2a + b	 


  • “b” represents the base of the Isosceles Triangle
  • “a” represents the leg of the Isosceles Triangle

How to find the area of the Isosceles Triangle?

By looking at the above formulas, you may have understood how to find the area of an Isosceles triangle. For your better understanding, we have solved an example here.

Example 1:

Find the area of an Isosceles triangle if the measure of its leg is 7 cm and its base is 5 cm.


We only have to use the following formula,

Area of an Isosceles Triangle = b/4 ✖ √4a2 - b2	

By putting the given values,

Area of an Isosceles Triangle = 5/4 ✖ √4(7)2 - (5)2 	

By solving the above equation, we get

= 16.35 cm2 	

How to use the Isosceles Triangle Calculator?

Finding different measurements using various formulas will take a lot of time and effort. It may be hard for you to accomplish the task with perfection. If you want to avoid mistakes, you should use this online tool Calculator’s Bag. Here are the simple steps you have to follow:

Step 1: Enter the value of the base in the first required input.

Step 2: Enter the value of height in the second required input.

Step 3: The calculator will automatically display an answer on the screen.

FAQ | Isosceles Triangle Calculator

Are all Isosceles triangles 45, 45, and 90?

Yes, all Isosceles has two equal angles of 45 degrees while the third angle of 90 degrees. But in a special case, this type of triangle will be converted to an equilateral triangle when all angles become equal.

Do Isosceles triangles sides add up to 180?

Yes, it is a general rule of a triangle that all internal angles will sum up to 180 degrees.

What is the rule of Isosceles triangle sides?

The rule for sides of an isosceles triangle is that it has two sides of equal measures.

How do you find the two missing angles of an Isosceles triangle?

If we have a base angle, we have to subtract it from 180 degrees and then divide it by two to get a measurement of one vertex angle. As an Isosceles triangle has two same vertex angles, it means that the angle you have found will be the same for the second missing angle.

How do I calculate the perimeter of an isosceles triangle given the leg and base?

To find the Perimeter of an Isosceles triangle, we have to use the following formula.

Perimeter of an Isosceles Triangle = 2a + b