In a rectangular trapezoid, the area is 30 cm2, the perimeter is 28 cm, and the smaller side is 3 cm

In a rectangular trapezoid, the area is 30 cm2, the perimeter is 28 cm, and the smaller side is 3 cm. Find the larger side.

The area of the trapezoid is equal to the product of the half-sum of the bases and the height.

Since the trapezoid is rectangular, the height of the trapezoid is equal to its side AB, then:

S = (AD + BC) * AB / 2.

30 = (AD + BC) * 3/2.

(АD + ВС) = 20 cm.

The perimeter of the trapezoid is:

P = AB + BC + CD + AD.

P = (AD + BC) + AB + CD.

Since (AD + BC) = 20 cm, then

28 = 20 + 3 + CD.

СD = 28 – 23 = 5 cm.

Answer: The large side is 5 cm.