Answer:
The length of the side of the triangle is 10 inches.
Explanation:
Let p = perimeter of the equilateral triangle
Let P = perimeter of the square
Let s = length of side of the triangle
Let S = length of side of the square
"The perimeter of an equilateral triangle is 6 inches more than the perimeter of a square"
p = P + 6 Equation 1
"the side of the triangle is 4 inches longer than the side of the square"
s = S + 4 Equation 2
We have 2 equations and 4 unknowns. We need two more equations. We use the definition of perimeter to get the other two equations.
For an equilateral triangle,
p = 3s Equation 3
For a square,
P = 4S Equation 4
Substitute p and P of Equation 1 with equations 3 and 4. Then write equation 2.
3s + 4S = 6
s = S + 4
Now we have a system of 2 equations in 2 unknowns. We can solve for s and S. We can use the substitution method. Solve the second equation for S.
S = 4 - s
Substitute S = 4 - s into equation 3s + 4S = 6.
3s + 4(4 - s) = 6
3s + 16 - 4s = 6
-s = -10
s = 10
Answer: The length of the side of the triangle is 10 inches.