Question

What is the exact circumference of the circle?
a.16cm
b.8cm
c.4cm
d.2cm

Answer 1

Answer: 8 cm

The diameter is the straight line across the circle, so, D= 8cm. A radius is half the diameter, so, since half of 8 is 4, R= 4. Then, we multiply the radius by 2, so we have

2 x R= ?. Since we know that R= 4, we get 2 x 4 = ?. 2 multiplied by 4 equals 8, therefore, our answer is 8cm.

Good luck!

Answer 2

B. 8π cm.

C = 2πr

The radius of the circle is 4 cm. (The radius is half of the diameter)
To find the exact circumference of a circle, you don't multiply by pi.
So take off the pi, 2 x 4 = 8

Now you add the pi symbol back on, 8π

You have your answer!