Use dot product methods to find the distance from (5,2) to the line 2x-7y=0.
I don't know about dot product methods, but note that the line can be rewritten as .
That means you're wanting to find the minimum distance between and .
The distance between these points is:
.
You should now be able to find the minimum distance, by taking the derivative, setting equal to 0 and solving, then using the second derivative test.