Radius of Smallest Circle in 6 Circles Problem (10cm)

[KKW]

If you inscribe 4 circles inside a bigger circle and then add another smaller circle, touching the other 4 circles, what is the radius of the smallest circle (in the centre) if the radius of the biggest circle is 10cm?

 

[dirk_mec1]

Is the radius of the four circles the same?

 

[Borek]

Assuming four circles are identical, that's everything you may need. Think how these are related to the radii of circles in question.