Which is more, 8 gallons or 28 quarts?

Which measure is equivalent to 110 ml? 0.0110 l 0.110 l 1.10 l 11,000 l

Evaluate cos2θ for cosθ = square root of 3/2

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?