Question 326795
An equilateral triangle is a triangle with all three sides of equal length.  So if we know the perimeter of a triangle is 21 inches, we can divide that by 3 to find the length of each side:
21/3 = 7
So each side of the triangle is 7 inches.
Now we will use the area of an equilateral triangle formula to solve the problem:
A = ((s^2)*(sqrt(3)))/4  where s = the length of a side
A = ((7^2)*(sqrt(3)))/4
A = (49*(sqrt(3)))/4
A = 21.2
So the area of the equilateral triangle is 21.2 square inches.