Co-ordinate Geometry with Circles

mattgad

New member
Joined
Oct 21, 2005
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41
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
 
Next time you have a problem similar to this,
get some graph paper and DRAW :idea:
 
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