The perimeter of the rectangle is 26 cm. The length of 1 side is 10 cm. Find the length of the adjacent side.

Since the opposite sides of the rectangle are equal, its perimeter is calculated by the formula:

P = 2a + 2b.

Provided that the sum of all sides of such a figure is 26 cm, and its length = 10 cm, we find the width by expressing it from this formula.

To find the second term, subtract the first from the sum:

2b = P – 2a = 26 – 2 * 10 = 26 – 20 = 6.

To find the factor, divide the product by the known one:

b = 6: 2 = 3 cm – is the width of the rectangle.