I been siting in one and a half hour trying to solve this problem, and i just can't do it. The picture is not exactly accurate, but i hope it will suffice. I really need help with this one. Please...
M is the the center of the cirkle. Prove that the distance A-B has the same distance as the radius of the cirkle.
The radius MB forms an angle of 30º with the chord BC. Then, angle ABM=60º. The radius MA is the side of an isosceles triangle where another side is MB (they are both radius, that is, they are equal). And then angle MAB=60. That implies that angle AMB is also equal to 60º and the third side's lenght is equal to the radius