Find the circumference

Step-by-step explanation:

A circumference of a circle can be determined by this: 2*pi*r

We're given the diameter. Divide that by 2 to get the radius.

6.45/2 = 3.225

Now multiply that by 2*pi. That gives us 2 * 3.14 * 3.225 = 20.253.

This could've also been done easier by doing pi*d where d is the diameter and you give the answer by multiplying them both. Also works, but the above formula is just key to many things and can also be used to derive the simpler one. Hope it helps! :)

10.6 feet, because you can use the Pythagorean theorem by the right triangle formed by the leaning ladder. 16 squared is 256, 12 squared is 144, and difference of the squares is 112, square root is 10.6. I hope my answer helped you to understand.