Please help me with this question, i really need helpp

1. are the triangles similar and if so why? what is the value of x? show your work.

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?

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2