1.
2. This one to me is a bit simpler, so you can try it out.
Think of it as a pythagorean triangle, draw a line from C to C1 and C1 to C2. It creates a right angle, so using this you can find the "hypotenuse."
When simplified, the answer is a radical.
3. If A'B' = 16 and A'B' = 3AB, what's AB? Easy problem.
Images from AoPS, thank you!
You are very welcome!
:P