# Homework Help: Use vectors to find coordinate of a point

1. Dec 16, 2013

### mesa

1. The problem statement, all variables and given/known data

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'

3. 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...

2. Dec 16, 2013

### SteamKing

Staff Emeritus
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.

3. Dec 16, 2013

### mesa

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 :)

4. Dec 17, 2013

### mesa

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