Circumference and Area of a Circle

Front

What is the formula for the circumference of a circle?

Back

The formula for the circumference (C) of a circle is C = πd or C = 2πr, where d is the diameter and r is the radius.

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle through its center, equal to twice the radius.

Front

How do you find the radius from the diameter?

Back

The radius (r) is half of the diameter (d). So, r = d/2.

Front

What is the area of a circle?

Back

The area (A) of a circle is given by the formula A = πr², where r is the radius.

Front

If the diameter of a circle is 10 cm, what is the radius?

Back

The radius is 5 cm, since r = d/2.

Front

Calculate the circumference of a circle with a diameter of 4 feet (use π = 3.14).

Back

The circumference is 12.56 feet.

Front

What is the relationship between diameter and circumference?

Back

The circumference is directly proportional to the diameter, expressed as C = πd.

Front

If the radius of a circle is 3 meters, what is the area?

Back

The area is 28.26 m², calculated using A = π(3)².

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

What is the formula for the area of a circle in terms of diameter?

Back

The area can also be expressed as A = (π/4)d².