The perimeter of the rectangle is 54 m, find the area of this rectangle if one of its sides is 18 cm.

| June 25, 2021 | education

Probably, the problem was written with an error, since when solving with the indicated units of measurement, ten-thousandths are obtained.

Let’s solve the problem, taking as a basis the unit of measurement cm (perimeter – 56 cm, side of the rectangle – 18 cm).

Since the perimeter of the rectangle and one of its sides are known, we can find the second side. The formula for the perimeter of a rectangle is: P = 2a + 2b, where P is the perimeter, a is one side, b is the other side. Take a side as the known side, then 2b = P – 2a; b = (P – 2a) / 2.

Find the length of side b.

(56 – 2 * 18) / 2 = (56 – 36) / 2 = 20/2 = 10 (cm) – the second side.

Now we can find the area. Formula for the area of ​​a rectangle: S = ab, where S is the area, a is one side, b is the other side.

18 * 10 = 180 (cm2) – the area of ​​the rectangle.

Answer: 180 cm2.



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