Question

A simple impact crater on the moon has a diameter of 15 kilometers. a complex impact crater has a radius of 30 kilometers. how much greater is the circumference of the complex crater than the simple impact crater?

Answer 1

The general equation for computing the circumference of a circle is
`C=\pi d`, where C is the circumference, and d is the diameter. (You might also see the equation as
`C=2 \pi r` where r is the radius, because
`d=2r`)

Computing the circumferences of the two circles, we get:

`C_(d=15)=\pi (15)=15\pi`

`C_(d=30)=\pi (30)=30\pi`.

To calculate the ratio of two numbers, we can divide one by the other. You can look at this as "How many times does the denominator fit in the numerator?"

`(C_(d=30))/(C_(d=15))=(30\pi)/(15\pi)=2`
So the circumference of the complex impact crater is 2 times greater than the circumference of the simple impact crater.