Illustrative Math Circle

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

• radius
• diameter
• circumference
• area

What is the diameter?

• 8
• 16
• 10
• 4

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

• Radius
• Diameter

A line that touches a curve at a point without crossing over

• Chord
• Secant
• Tangent
• Semicircle

The distance around a circle

• Diameter
• Radius
• Circumference
• Area

What is the formula for circumference of a circle given the diameter?

• C = π r
• C = 2 π r
• C = π d
• C = 2 π d

find the area of the circle below.

• 100 cm
• 225 cm
• 9 cm
• 28.26 cm

A line segment on the interior of a circle with endpoints on the circle

• Radius
• Diameter
• Secant
• Chord

Steven purchases a bowl. The diameter of the
bowl is 14 cm. What is the circumference of the 
bowl?

• 28 cm
• 43.98 cm
• 87.96 cm
• 7 cm

The Death Star is believed to have had a diameter of around 150 km. What is the radius of the Death Star?

• 300 km.

• 75 km.

• 22,500 km.

• 150 km.