Circumference & Area of Circles Quick Check
1. What is the formula for the circumference of a circle?
- The formula for the circumference of a circle is C = 2πr, where C is the circumference and r is the radius of the circle.
2. What is the formula for the area of a circle?
- The formula for the area of a circle is A = πr^2, where A is the area and r is the radius of the circle.
3. If the radius of a circle is 3 cm, what is the circumference?
- Using the formula C = 2πr, with r = 3 cm, the circumference is C = 2π(3) = 6π cm or approximately 18.85 cm.
4. If the radius of a circle is 5 cm, what is the area?
- Using the formula A = πr^2, with r = 5 cm, the area is A = π(5)^2 = 25π cm^2 or approximately 78.54 cm^2.
5. Which measurement (circumference or area) is affected by changing the radius of a circle?
- Both measurement, circumference and area, are affected by changing the radius of a circle. The circumference is directly proportional to the radius, while the area is proportional to the square of the radius.