A triangle can be classified based on the sides and sides. Based on the sides, a triangle can be classified into three types namely,
- Scalene Triangle
- Isosceles Triangle
- Equilateral Triangle
Based on the angles, a triangle can be classified into three types namely,
- Acute Angle Triangle
- Obtuse Angle Triangle
- Right Angle Triangle
In this article, we are going to discuss one of the types of triangles called “Isosceles Triangle” in detail.
- Isosceles Triangle, Equilateral Triangle, Scalene Triangle
- Isosceles Triangle Theorem
- Area of Isosceles Triangle
- Isosceles Triangle Formula
Isosceles Triangle Definition
An Isosceles triangle is a triangle which has two equal sides. Also, the two angles opposite to the two equal sides are equal. Suppose in a triangle △ABC, if sides AB and AC are equal, then △ ABC is an isosceles triangle where ∠ B = ∠ C.
The triangle having all the three sides equal is called an Equilateral triangle. Also, the triangle having all the three unequal sides is called a Scalene triangle.
Isosceles Triangle Properties
- As the two sides are equal in this triangle, the unequal side is called the base of the triangle.
- The angles opposite to the two equal sides of the triangle is always equal.
- The altitude of an isosceles triangle is measured from the base to the vertex(topmost ) of the triangle.
- A right isosceles triangle has the third angle as 90 degrees.
Isosceles Triangle Area
The area of an isosceles triangle is = ½ × b × h, where b is the base and h is the height of the triangle.
A = ½ × b × h
Example: Find the area of an isosceles triangle given its height as 6 cm and base as 4 cm?
Solution: Area of an isosceles triangle is ½ × b × h
A = ½ × 4 × 6 = 12 cm2
Isosceles Triangle Perimeter
As we know the perimeter of any shape is the boundary of the shape. Similarly, perimeter of an isosceles triangle can be found if we know its base and side.
P = 2a + b, where ‘a’ are the two equal sides of the triangle and b is the base of the triangle.
Example: Find the perimeter of an isosceles triangle, with side 6 cm and base 4 cm.
Solution : P = 2a + b = 2(6) + 4 = 12 + 4 = 16 cm
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