A circle with the radius of 6cm sits inside a circle with radius of 9 cm

Which expression is equivalent to? assume x > 0 and y > 0.

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?

An equation in slope-intersept form the lines that passes thought (-8,1) and is perpindicular to the y=2x-17.