Question

In finding the perimeter of which of these shapes we will use minimum number of variables?

• A. Equal number of variables for all of them
• B. Isosceles Triangle
• C. Equilateral Triangle
• D. Rectangle

Answer 1

The correct option is C Equilateral Triangle

We will use variables for all the unknow values in finding perimeter of all these shapes.

An equilateral triangle has all equal sides. Let us denote length of each side by a variable 'a'.
So, its perimeter = 3 $\times$ a
= 3a

In an isosceles triangle only two sides are equal. So, for the measure of equal sides we use a variable 'a', and we use one more variable 'b' for the measure of the third side.
So, its perimeter = 2 $\times$ a + b
= 2a + b

In a rectangle the opposite sides are equal, so we use two variables for finding its perimeter.
So, the perimeter of the rectangle
= 2 $\times$ a + 2 $\times$ b
= 2a + 2b

So, we can say that in the given options, we need minimum number of variables for finding the perimeter of an equilateral triangle.