Perimeter of a Triangle Examples

Example 1: If the length of the sides of a triangle is 4cm, 5cm, and 6cm, then what is the perimeter of the triangle?

Solution:

Given, the sides of the triangle are 4cm, 5cm, and 6cm. Thus, it is an scalene triangle.

So the perimeter of the triangle  = Sum of sides = 4 + 5 + 6 = 15cm

Example 2: In an isosceles triangle, the two sides are given as 5cm and 6cm. What can be the perimeter of the triangle?

Solution:

Given, the triangle is the isosceles triangle. Thus, any two sides of the triangle are equal.

So, the third side can be either 5cm or 6cm.

If the third side is 5cm, then,

Perimeter = 5 + 5 + 6 = 16cm

If the third side is 6cm, then,

Perimeter = 5 + 6 + 6 = 17cm

So, the perimeter can be either 16cm or 17cm.

Example 3: What is the perimeter of an equilateral triangle whose one side length is 5cm?

Solution:

Given that the triangle is an equilateral triangle, thus all three sides are equal in length.

Since one side is equal to 5cm, the other two sides will also be equal to 5cm.

So, Perimeter = 5 + 5 + 5 = 15cm.

Example 4: Given the perimeter of an equilateral triangle is 21cm, find the length of its three sides.

Solution:

Since, in an equilateral triangle, all the three sides are equal in length, the perimeter is equal to three times the length of a side.

Let’s the length of any side be equal to ‘a’ units. So perimeter is equal to ‘3a’ units.

So, we can write,

3a = 21

a = 7cm

Thus, the length of each side is equal to 7cm.

Example 5: Find the length of two equal sides of an isosceles triangle if the length of the unequal side is 5cm and the perimeter is 17cm.

Solution:

Given, the length of unequal side is 5cm and perimeter is 17cm.

Since, it is isosceles triangle, length of other two sides are equal. Let each equal side length be ‘a’ units.

Thus, perimeter = a + a + 5

Since, perimeter = 17cm, we can write,

17 = a + a + 5

2a + 5 = 17

2a = 12

a = 6cm

Thus, the length of the equal sides of the isosceles triangle is 6cm.

Perimeter of Triangle is the total length of all its three sides. A triangle is a polygon that has three sides or edges, three vertices, as well as three angles, hence the name triangle. The triangle is the most fundamental closed polygon in geometry, as it is the first possible closed polygon. With only two vertices, we can only form a line, not any closed polygon. Additionally, we can divide any polygon into triangles. For example, we can divide a quadrilateral using its diagonal into two triangles, a pentagon using two diagonals from the same vertex into three triangles, and so on.

In this article, we have provided all the important details related to like its definition, the formula for perimeter of triangle, and how to find the perimeter of triangle.