# Finding a point distance n between two points.

• Dec 6th 2009, 09:57 AM
ccsutton
Finding a point distance n between two points.
It's been years since I've had to use algebra and this problem is driving me crazy.

I have point A(5651,4768) and point B(5649,4742).

I want to find a point C(x,y) that is distance 15 from point A, along the line AC.

I've sort of figured it out, but I don't know how to express Cx=?? and Cy=?? in equation form.
• Dec 6th 2009, 10:02 AM
Jhevon
Quote:

Originally Posted by ccsutton
It's been years since I've had to use algebra and this problem is driving me crazy.

I have point A(5651,4768) and point B(5649,4742).

I want to find a point C(x,y) that is distance 15 from point A, along the line AC.

I've sort of figured it out, but I don't know how to express Cx=?? and Cy=?? in equation form.

By the distance formula, we want

$\displaystyle 15 = \sqrt{(x - 5651)^2 + (y - 4768)^2}$

Find the equation of the line connecting points A and B in terms of x, and then replace y with that expression in the above formula. Solve for x and you are on your way