How to find the side of a rectangle if you know the perimeter 172 side a 43.

1. Since we know from the problem statement that the length of one of the sides of the rectangle is 43 cm, therefore we can find out the sum of these two sides.
43 + 43 = 86 cm.
2. And now we can calculate the sum of the lengths of the other two sides of the rectangle, if the problem statement says that its perimeter is 172 cm.
172 – 86 = 86 cm.
3. Now let’s calculate what the length of the second side of the rectangle is, dividing the found sum by 2.
86/2 = 43 cm.
Since all sides of the rectangle are equal, it is a square.