Use vectors to find coordinate of a point

[mesa]

Homework Statement

So for this problem we are shown a right triangle with point B at (2,1), C at (7,0) and A(x,y). 'A' also happens to rest at the right angle of our triangle. What is the coordinate of 'A'

The Attempt at a Solution

I tried this one a couple ways. For example the dot product of AB and AC will be zero but that gets messy. I then tried using the magnitude of each vector and used Pythagoras but it gets messy that way too. I am sure it is something simple but it's been a long night...

 

[SteamKing]

It probably is. Right triangles are tricky that way. However, you have shown no work, and it is difficult to see where you went so horribly wrong.

 

[mesa]

It probably is. Right triangles are tricky that way. However, you have shown no work, and it is difficult to see where you went so horribly wrong.

Sorry, I thought my method was at issue... It is funny how sometimes when re-writing on a keyboard a problem can fix itself. My ^2 terms canceled so I am good to go, it pays to follow protocol :)

 

[mesa]

Not that I am bothered by it, I simply want to know why this thread was 'moved'?