Perimeter of a Triangle Definition
- Perimeter of a triangle is the total length of the sides of a triangle. The sides of the triangle may be equal or unique.
- If all the three sides are same, then it is known as an equilateral triangle.
- It is an isosceles triangle if two of the sides are equal.
- For a triangle to exist certain conditions need to be met. For any triangle, one of the following three conditions must be true.
- a + b > c
- b + c > a
- c + a > b
Now, the formula for the Perimeter of a Triangle is given as,
a, b, c are the sides of the triangle.
Question 1: Find the perimeter of a triangle whose sides are of 6 cm, 8 cm and 12 cm.
a = 6 cm
b = 8 cm
c = 12 cm
Perimeter of a Triangle = a + b + c
= 6 + 8 + 12
= 26 cm
Question 2: Find the perimeter of an equilateral triangle whose side is 6 cm.
Being an equilateral triangle, all the sides are equal.
Thus, a = 6
Perimeter of an equilateral triangle= a + b + c = a + a + a = 3a
= 3 x a
= 3 x 6
= 18 cm
Question 3: Find the perimeter of an isosceles triangle whose equal sides measure 6 cm and the third side is 8 cm.
Being an isosceles triangle, two sides are equal.
Thus, a = 6, b = 6 and c = 8
Perimeter of an isosceles triangle= a +b + c = a + a + c = 2a + c
= 2 x 6 + 8
= 12 + 8
= 20 cm
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