Bonus: The cube shown below has edges of length

4 and A and B are midpoints of two of the

edges. What is the length of segment AB

(not shown)? Give an exact answer.

The cube shown below has edges of length

6 and A and B are midpoints of two of the

edges. What is the length of segment AB

(not shown)? Give an exact answer.

I

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?