Isosceles Triangles Formulas

The height, perimeter, and area are the three basic formulas of an isosceles triangle, which are discussed below.

Perimeter of Isosceles Triangle

The perimeter of an isosceles triangle is equal to the sum of its three side lengths. As an isosceles triangle has two equal sides, the perimeter of the isosceles triangle will be (2a + b) units, where “a” is the length of the two equal sides and “b” is the base length.

Perimeter of an Isosceles Triangle = (2a + b) units

Where,

• “a” is the length of the two equal sides, and
• “b” is the base length

Learn more about, Perimeter of a Triangle

Isosceles Triangle Area

The total region bounded by the three sides of a triangle in a two-dimensional plane is known as the area of a triangle. The area of an isosceles triangle is equal to half the product of its base length and its height.

Area of an Isosceles Triangle = ½ × base × height

• If the three side lengths of an isosceles triangle are given, then its area can be calculated using Heron’s formula.

Area of an Isosceles Triangle = [Tex]\frac{1}{2}\times b\times\sqrt{[a^{2}-(b/2)^{2}]}[/Tex]

where,

• “a” is Length of Two Equal Sides
• “b” is Base Length

Isosceles Triangle Altitude

Perpendicular drawn from the apex angle bisects the base of the isosceles triangle and the apex angle. The formula to calculate the height of an isosceles triangle if its side lengths are given is as follows:

Height of an Isosceles Triangle (h) =[Tex]\sqrt{[a^{2}-(b/2)^{2}]}[/Tex]

where,

• “a” is Length of Two Equal Sides
• “b” is Base Length

An Isosceles triangle is defined as a triangle that has two equal sides. We know that a triangle has three angles and if any two of them are equal we call this triangle an Isosceles triangle as well. Thus, we can say that if a triangle has two sides equal and two angles equal then it is an isosceles triangle.

Triangle is divided into three categories based on the equality of side length.

• Scalene Triangle (All three sides are unequal)
• Isosceles Triangle (Only two sides are equal)
• Equilateral Triangle (All three sides are equal)

In this article, we will learn about the area of the isosceles triangle, its perimeters, properties, examples, and others in detail.