What is the area of a circular aluminum plate with a diameter of 7 feet, when rounded up?

To find the area of a circular aluminum plate, you use the formula for the area of a circle, which is A = πr², where A is the area and r is the radius of the circle.

First, you need to determine the radius of the plate. Since the diameter is given as 7 feet, you calculate the radius by dividing the diameter by 2.

Radius (r) = Diameter / 2 = 7 feet / 2 = 3.5 feet.

Next, you plug the radius into the area formula:

A = π(3.5)² = π(12.25).

Using the approximate value of π (about 3.14), you can calculate the area:

A ≈ 3.14 × 12.25 ≈ 38.5 square feet.

When rounding this value up, the area becomes 39 square feet. Therefore, the choice that reflects the area of the circular aluminum plate, when rounded, is the correct answer.