Formula Fun
Real-World Circles
Circle Parts
Fun Facts
100

What is the formula for the area of a circle?

A=(PI)R2

100

Name a real-world object that is circular.

What is a coin (or a clock, pizza, plate, wheel, etc.)?

100

What is a radius?

What is the distance from the center of the circle to the edge?

100

What number is used in the area formula?

What is π (pi)?

200

How do you find the radius from the area?

What is taking the square root of the area divided by π?

200

How is the area of a circle useful in real life?

What is figuring out the size of things like pizzas, gardens, pools, or circular tables?

200

What is a diameter?

What is the distance across the circle through its center?

200

What is pi (π)?

What is the ratio of a circle’s circumference to its diameter?

300

What is the area of a circle with a radius of 5 cm?

What is 78.5 cm²?

300

Calculate the area of a pizza with a diameter of 12 inches.

What is 113.1 in²?

300

How are radius and diameter related?

What is the diameter equals two times the radius?

300

Why is pi (π) important in circles?

What is because it connects the circle’s circumference, diameter, and area formulas?

400

If the area is 78.5 cm², what is the radius?

What is 5 cm?

400

 A circular garden has a radius of 7 ft. What is its area?

What is 153.9 ft²?

400

What is the circumference of a circle?

What is C = 2πr

400

What is the approximate value of pi (π)?

What is about 3.14 (or 22/7)?

500

 Explain why the area of a circle is measured in square units.

What is because area measures the amount of space inside a shape, and that space is always measured in square units?

500

How does the area of a circle compare to that of a square with the same diameter?

What is that a circle has less area than a square with the same diameter because the square covers all four corners while the circle only fits inside?

500

How does changing the radius affect the area?

What is doubling the radius makes the area four times larger because the radius is squared in the formula?

500

Name two famous mathematicians who contributed to the study of circles



Who are Euclid and Archimedes?

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