Equation: 4s=s+9
a. Subtract s from both sides.
4s-s=9
Simplify.
3s=9
Divide both sides by 3.
s=3
A side length of the equilateral triangle is 3.
b. To verify, substitute 3 for s in the equation.
4(3)=3+9
12=3+9
12=12, so it is correct.
c. Since it is an equilateral triangle, each side is the same. If one side of the triangle is 3 and there are 3 sides, you can multiply 3*3 to find the perimeter.
3*3=9, so the perimeter is 9.
I hope this helps :)
