Calculating Circumference and Area of Circles

What is the radius of a circle if its diameter is 8 units?

• 2 units

• 4 units

• 8 units

• 16 units

If a circle has a diameter of 10 units, what is its radius?

• 5 units

• 10 units

• 20 units

• 2.5 units

Who is credited with thinking deeply about the ratio of a circle's circumference to its diameter?

• Einstein

• Newton

• Archimedes

• Pythagoras

What is the approximate value of Pi?

• 2.18

• 3.14

• 3.56

• 4.22

How do you calculate the circumference of a circle?

• Radius plus Pi

• Diameter divided by Pi

• Radius times Pi

• Pi times diameter

If the radius of a circle is 7 units, what is its circumference using Pi as 3.14?

• 14 units

• 44 units

• 21.98 units

• 43.96 units

If the circumference of a circle is 31.4 units and Pi is 3.14, what is the diameter?

• 5 units

• 15 units

• 10 units

• 20 units

What is the formula to calculate the area of a circle?

• Pi * Radius

• Pi * Diameter

• Pi * Radius squared

• Pi * Diameter squared

What is the area of a circle with a radius of 3 units using Pi as 3.14?

• 9.42 units squared

• 18.84 units squared

• 56.52 units squared

• 28.26 units squared

A circle's area is 50.24 inches squared using Pi as 3.14. What was the radius?

• 6 inches

• 2 inches

• 8 inches

• 4 inches