A circle has an area of . What is its circumference?

The area of the semicircle above is . What is the length of the arc connecting points A and B?

In the circle above, centered on point O, angle AOB measures 40 degrees. If line segment BD measures 18 inches, what is the measure, in inches, of minor arc BC?

A gas pipe has an outside diameter of 24 inches. The steel wall of the pipe is 1 inch thick. What is the area of the cross-section of the steel wall of the pipe?

In the figure above, AC is the diameter of a circle with center O. If the area of the circle is , what is the length of minor arc BC?

A pizzeria measures its pizzas by their diameters when listing sizes on the menu. What is the difference, in square inches, in surface area between a 10-inch pizza and an 8-inch pizza from that pizzeria (assume that each pizza has a negligible height/thickness)?

What is the area of a circle with a circumference of ?

If the circle above has center A and area , what is the perimeter of sector ABCD?

A bicycle tire has a diameter of 70 centimeters. Approximately how many revolutions does the tire make if the bicycle travels 1 kilometer? (1 kilometer = 1000 meters = 100000 centimeters)

On a certain circular dartboard, the diameter of the circular bullseye is 4 inches and the diameter of the entire board is 20 inches. If a dart hits the board in a random location, what is the probability that it hits the bullseye target?