Question

I need help with b please.

Answer 1

If I am doing this correctly, the perimeter is 21. So add 7+7+7=21. I suggest dividing the perimeter by the number of faces on the shape to find the length of each face or line.


`21 / 3 = 7`

Answer 2

Since all the sides are x, you can say that the triangle is an equilateral triangle, because all the sides are equivalent. You know that the perimeter is 21cm, so x+x+x must equal 21.
Your equation is x + x + x = 21, or 3x = 21.
Divide both sides by 3.
x = 7