# Equation of the line joining A(-1, 9) to B(6, 12)

1. Oct 10, 2004

### omicron

1.Find the equation of the line joining A(-1, 9) to B(6, 12).
Another line passes through C(7, -5) and meets AB at right angles at D.
Find the equation of CD and calculate the coordinates of D.

Given That the coordinates of M are (K, -2K) and that the distance of AM is $$\sqrt{178}units$$, calculate the value of K.

How do i calculate the value of K?

2. Q is the reflection of the point(2,9) in the straight line y = 2x. Calculate the coordinates of Q.

Last edited: Oct 10, 2004
2. Oct 10, 2004

### rhia

|AM|^2=[(K+1)^2 + (-2K-9)^2] = 178 => K=2
If Q is the reflection of Q about the line y=2x then the line y=2x is the perpendicular bisector of QQ. QQ has slope = -1/2 .Find the intersection pt.
which is the mid-pt of QQ.

nb

3. Oct 10, 2004

Thanks....