Here's the question you clicked on:
ERoseM
Find an equation for all coplanar points whose distances from (2,3) and (8,3) have a constant difference of 4. I think you have to use the distance formula
Sounds like a hyperbola..
Let's say we pick some arbitrary point \((x,y)\) in the plane. What is the distance from that point to the two given points? (Hint: use the distance formula, which is just an application of the Pythagorean theorem \(a^2+b^2=c^2\)).