Pls help me I’m having a hard time

Fast phone couldn’t copy and paste so i decided to right it down

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?

Given: pb tangent pv,pu secants if m = 80° and m = 30°, then m 3 = 55 40 25