Question

The perimeter of an equilateral triangle is 9 inches more than the perimeter of a​ square, and the side of the triangle is 5 inches longer than the side of the square. Find the side of the triangle.​

Answer 1

11 inches.

Explanation:

Let the side of the triangle be x inches.

Then the perimeter = 3x inches (as all 3 sides are equal).

If one side of the square is y inches then its perimeter is 4y inches.

So,

3x = 4y + 9

x = y + 5

Substitute x = y + 5 in the first equation:

3(y + 5) = 4y + 9

3y + 15 = 4y + 9

15 - 9 = 4y - 3y

y = 6.

So, substituting for y in second equation:

x = 6 + 5

= 11.