android
Contributor
dlndavid:Understanding simple geometry will allow you to aim a mirror.
Use the force Luke.
And have you ever used a CD to shave? I didn't think so.
Geometry is just not enough to aim a mirror or CD. Give it a try (I have) Find a nice reflective traffic sign. Now go about 1/2 mile down the road. Aim at the sign and flash it. When you hit it, you will know, because it will light up. Try with a CD. Try with a real signal mirror like a Rescue Reflector or StarFlash. Think about how hard it will be to hit a boat or plane while you're lost at sea. Especially a plane since there will be no reference point in the air. Throw CD in trash.
(Yes, I know you can sight a mirror using your fingers. This method sucks and nobody recommends it.)