Exploring Circumference and Area of Circles

What is the formula for the circumference of a circle if the diameter is known?

• A = 2πr^2

• A = πr^2

• C = 2πr

• C = πd

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

• 4 units

• 16 units

• 8 units

• 12 units

If the diameter of a circle is 14 units, what is the radius?

• 21 units

• 14 units

• 28 units

• 7 units

How do you calculate the radius if the circumference is given?

• R = 2C / π

• R = C / 2π

• R = C / (π^2)

• R = C / π

How do you find the circumference if the radius is given?

• C = r^2π

• C = r/π

• C = 2πr

• C = πr

Given the circumference is 62.8 units, what is the approximate diameter?

• 30 units

• 40 units

• 20 units

• 10 units

What is the area of a circle with a radius of 3 units?

• 6π units^2

• 9π units^2

• 12π units^2

• 18π units^2

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

• A = 2πr

• A = πr^2

• A = r/π

• A = πr

If the area of a circle is 50π square units, what is the radius?

• 10 units

• 5 units

• 25 units

• 7.5 units

If the area of a circle is 314 units squared, what is the approximate radius?

• 20 units

• 10 units

• 15 units

• 5 units