(1) The distance from the center O to CD is actually the height of the parallelogram with AB as the base, and it is set as x.

The height of the parallelogram with BC as the base is AB×sin60 degrees =5 times the root number 3.

The area of parallelogram is fixed.

So CB×5 times the root number 3 = ab × X.

M×5 times the root number 3= 10x.

So x= (root number 3/10) m.

(2)CD is tangent to the circle, that is, when the height of the parallelogram with AB as the base is the radius of the circle 5.

So AB×5=m×5 times the root number 3.

That is, 10×5=m×5 times the root number 3.

Therefore, m=50/5 times the root number 3= 10/ root number 3=( 10 times the root number 3)/3.