Area & Circumference of Circles

If my diameter is 19 inches, what is my radius?

• 38 inches
• 9.5 inches
• 59.66 inches
• 119.32 inches

If my radius is 10ft, what is my diameter?

• 20ft
• 5ft
• 31.4ft
• 62.8ft

what is the circumference of this circle ?

• 3.14 cm 
• 37.68 cm
• 24 cm
• 68.4 cm

A cruise ship has a large, circular window. It has a diameter of 6 meters. What is the window's area?

• 31.25 m²
• 29.55 m²
• 30.36 m²
• 28.26 m²

Does this picture show the diameter or radius of a circle?

• Diameter
• Radius

Is the red line a radius or diameter of the circle?

• Radius
• Diameter

 What are the formulas for circumference of a circle?

• C = π r

• C = π d

• C = 2 π r

• C = 2 π d

How do you find the area of a circle?

The distance halfway across the circle is called the...

• radius

• diameter

• circumference

• area

What is the radius of this circle?

• 18
• 36
• 9
• 6