Re: Min. Distance


Virgil wrote:
In article <BJafg.11$ex3.7@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Jackie Chan" <JackieChan@xxxxxxxxxxxxxxxx> wrote:

Q: What is the min distance between these two lines:
Equation #1: y = 3/2 x + 9
Equation #2: y = 3/2 x -4
a) 5.83
b) 6.50
c) 7.21

This (c) is the correct answer. I'm just an old engineer, but this
problem is trivially easy. Just sketch it, and by inspection, the
answer is, by proportion, twice the Y-separation between the two
(obviously parallel) lines divided by the square root of that
separation:

d = 2*13/sqrt(13)= 2*sqrt(13)=7.211.....

Why make something harder than it really is? Sheesh!

Regards,

Grover Hughes



d) 9.19
e) 13.00

The distance from point (u,v) to line y = m*x + b

is given by | m*u + b - y | / sqrt(1 + m^2)

.