Co-ordinate Geometry with Circles

[mattgad]

Question:

The circle, centre (p, q) has radius 25, meets the x axis at (-7, 0) and (7, 0), where q > 0. Find the value of p and q.

What I have tried so far:

Formed an equation -
$\displaystyle (x - p)^2 + (y - q)^2 = 625$

Tried to sub in x = 7 and y = 0,

$\displaystyle (7 - p)^2 + q^2 = 625$

$\displaystyle 7 - p + q = 25$

$\displaystyle 7 - p = 25 - q$

-p = 25 - q - 7

$\displaystyle p = q - 25 + 7$

$\displaystyle p = q - 18$

Can someone point me in the right direction to get the answer of p = 0, q = 24

Thanks

 

[mattgad]

Problem solved thanks to Unco.

 

[Denis]

Next time you have a problem similar to this,
get some graph paper and DRAW :idea: