2)

A circle has a radius of 8 cm. What is its circumference?

8 cm

Answer

16π cm ≈ 50.2655 cm

Step-by-step explanation

To find the circumference of a circle, we can use the equation C = 2πr.

C stands for the circumference while r stands for the radius. We can see that there is a proportional positive linear relationship between radius and circumference for all circles, and that to find circumference when we have a radius value, we multiply the radius value by 2π.

The value of π, also called pi, is a constant and is the ratio of a circle's circumference to its diameter (the diameter is twice the radius, hence the 2 in the equation). Note that π is a constant and applies to all circles because all circles are similar.

Since we know the value of r, or the radius, given as 8 cm in the question, we can plug this value into the equation C = 2πr from earlier.

C = 2πr (plug in 8 cm for the radius)

C = 2π * 8

C = 16π cm

Since the radius is in units of cm (centimeters), the circumference is also in units of cm (centimeters).

16π cm is the exact value of the circumference. However, if we want this circumference in decimal form, we would multiply 16 by the decimal form of π which is approximately 3.1416. Note that π actually has an infinite amount of decimals and that this 3.1416 is actually a rounded π value

C = 16π

C ≈ 16 * 3.1416

C ≈ 50.2655 cm rounded to four decimal places