Question

What do you notice about the ratio of the distance around the circle to the distance across the circle for each circle?

Answer 1

Remember that

the circumference of a circle is equal to

$C=\pi\cdot D$

the distance across the circle is equal to the diameter D

so

the ratio is equal to

$\text{ratio}=\frac{C}{D}=\frac{\pi\cdot D}{D}=\pi$

For each circle the ratio is equal to the number pi