Question

Use your notebook to answer the following question
1. The perimeter of a triangle is 21 cm. If
two of its sides are 7 cm each, what is
the length of the third side? What type of
triangle is this?​

Answer 1

Answer:

7 cm and Equilateral triangle

Step-by-step explanation:

We know that formula for perimeter of triangle = sum of three sides.

Consider a , b , c as the sides of triangle

then perimeter = a + b + c

Given, Perimeter = 21 cm.

Two sides of triangle are 7 cm each i..e a = b = 7 cm.

a + b + c = 21

=> 7  + 7 + c = 21

=> c = 21 - 14 = 7 cm.

Thus length of third side is 7 cm.

Since all the three sides are equal, it is an Equilateral triangle.