Find the area of a circle

When a circle is cut into many equal pie-shaped pieces and rearranged, the result resembles a parallelogram whose base is half the circumference and whose height equals the radius.

The area of a circle with radius \(r\) is given by the formula:

\[A = \pi r^2\]

In the expression \(\pi r^2\), what operations are indicated?

Before computing the area of the circle below, the radius must be found. The diameter is labeled on the figure.

Since the length of the diameter is 10 cm and the diameter is twice the length of the radius, what is the radius?

Find the exact area of the circle shown below. Leave the answer in terms of \(\pi\).

The exact area of the circle with diameter 10 cm is \(25\pi\) cm². Using a calculator, approximate the area to the nearest tenth.

Find the exact area of a circle with a diameter of 12 feet. Leave the answer in terms of \(\pi\).

The exact area of the circle with diameter 12 ft is \(36\pi\) ft². Approximate the area to the nearest tenth.

Orange paint is available in gallon containers at $19 each, and each gallon covers 375 ft². A circular helicopter landing pad has a diameter of 60 feet. How much will it cost to paint the pad?

How many gallons of paint must be purchased, and what is the total cost?

Find the area of the shaded figure below. Round to the nearest hundredth.

Find the area of the shaded figure below. Round to the nearest hundredth.

Drag the correct expression into each placeholder.

Full circle area: \(A = \pi\) × 1($)

Semicircle area: \(A = \) 2($) \(\times \pi r^2\)

In the 6–8–10 composite figure:
Triangle area = ½ × 6 × 8 = 3($) in²
Smaller semicircle (\(r=4\)) area = 4($) \(\pi\) in²
Larger semicircle (\(r=5\)) area = 5($) \(\pi\) in²