# Thread: not sure if this is actually calculus

1. ## not sure if this is actually calculus

point P (a,b) is equidistant from the point (4,0) and the y axis.
Find a relationship between a and b
merci d'avance
kop forever

2. Originally Posted by scouser
point P (a,b) is equidistant from the point (4,0) and the y axis.
Find a relationship between a and b
merci d'avance
kop forever
Draw a diagram.

$\displaystyle a = \sqrt{b^2 + (a - 4)^2}$.

3. yes, but why? of course i drew a diagram and i have the answer, but i have to know why otherwise i won't learn anything. is mr.fantastic a real person or some program? sorry i'm new...

4. Originally Posted by scouser
yes, but why? of course i drew a diagram and i have the answer, but i have to know why otherwise i won't learn anything. is mr.fantastic a real person or some program? sorry i'm new...
The distance of $\displaystyle (a, b)$ from the y-axis is $\displaystyle a$ (since $\displaystyle a > 0$. Why?). The distance of $\displaystyle (a, b)$ from $\displaystyle (4, 0)$ is given by the usual distance formula.