∴∠CBO=90，

Let o' be the center of the circle determined by o, b and C.

Then OC is the diameter of ⊙O'.

From the known OB=6, CB=8, from Pythagorean theorem, OC= 82+62= 100= 10.

Radius OO'=5, S⊙O'=π? 52=25π.