A motorist travels from a town P on a bearing of 150°to a town Q 40km away. From Q he travels to a town R on a bearing of 210°if R you s located directly south of P, how far is R from P?(a)40√3km(b)40√2km(c)40km(d)80km​

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?