Answer:
10 cms.
Explanation:
The circumcircle passes through each vertex of the hexagon so the radius is equal to one of the 2 equal sides of an isosceles triangle with base = 10 cm and vertex = 60 degrees.
So considering this triangle the base angles are ( 180 - 60) / 2 = 60 degrees. So we have an equilateral triangle with each side = 10 cm.
Therefore the radius is 10 cm. long.