Asimple 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?

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

Computing the circumferences of the two circles, we get:

.

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?"

So the circumference of the complex impact crater is 2 times greater than the circumference of the simple impact crater.

Add up all the sides