Can someone please help me with this problem for a medal? I have the solution. I'm just not sure what's going in it. (posting picture below)

Question

anonymous · Answer

attachment

anonymous · Answer

anonymous · Answer

Which topic is this? Have you learned the distance formula? :)

anonymous · Answer

@mathway 
I'm in calculus, and yes I've learned the distance formula.

anonymous · Answer

@satellite73 
That doesn't have trig in it does it? (I don't see any, but I just thought I'd ask in case you see something I don't)

anonymous · Answer

attachment

anonymous · Answer

The solution is above. ^

anonymous · Answer

@zepdrix 
Are you good with calculus?

zepdrix · Answer

Sec :) going through the steps.
I'm not really familiar with this problem.

zepdrix · Answer

And my internet connection being bad tonight :(
Not sure if I'll be able to stay connected.

zepdrix · Answer

|dw:1448253453132:dw|So let's call the length of the board L, as they did in the solution.