If △abc is a dilation of △def with a scale factor of 8, which statement must be true? you cannot assume any relationship between the triangles. △abc≅△def none of these statements are true. △abc∼△def

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?