Circles and Ratios

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

• Radius

• Diameter

A bike wheel has a diameter of 10 in. What is the circumference of the wheel? Use 3.14 for π.

A hula hoop measures 14 inches from the center to the outside. What is the distance around the hula hoop?

• 21.98 in

• 175.84 in

• 43.96 in

• 87.92 in

The radius of a circle is

• The measurement from the center of a circle to the edge of the circle.

• The measurement around the circle

• The measurement from the edge of the circle to another edge through the center

• A line perpendicular to the diameter of the circle

If you are given the radius, how can you calculate the diameter?

• Multiply the radius by 2

• Divide the radius by 2

• Add 2 to the radius

• Subtract 2 from the radius

The diameter of a circle is

• The measurement from the center of the circle to the edge of the circle

• The distance around a circle

• The measurement from the edge of the circle to another edge through the center

• A line perpendicular to the diameter of the circle

If you are given the diameter, how can you calculate the radius?

• Multiply the diameter by 2

• Divide the diameter by 2

• Add 2 to the diameter

• Subtract 2 from the diameter

What is circumference?

• The distance around a circle

• The measure of the space inside a circle

• The measurement from the edge of the circle to another edge through the center

• The measurement from the center of the circle to the edge of the circle

What is the formula for the circumference of a circle?

• C=πd

• C=πd²

• A=πr²

• A = bh

What is the area of a circle?

• The distance around a circle

• The measurement of the space inside a circle

• The measurement from the edge of the circle to another edge through the center

• The measurement from the center of a circle to the edge of the circle