# Circle Problem!

Geometry Level pending

Assume you have an empty plane.In that plane there is a straight line.Tangent to the line ,above it,we have $$3$$ circles which are also tangent to each other.There is one small circle in the middle.In the left there is a big circle and in the right there is an average circle.If the radius of the big circle and average circle are $$72$$ and $$18$$ respectively,then find the radius of the smaller circle.(Yes, the big circle and the average circle are tangent to each other and to the small circle in the middle simultaneously.)

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