Find the range of the function. f(x) = 10 x²
a. [5...)
b. (-0, -1) U (0...)
c. (-0, 10]
d. (-0..-1) U [... 10)

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?