Hi,

Clearly, this problem has been designed to be very easy for those who know some geometry, and much harder for those who fail to use the familiar theorems. Draw a picture to scale. What’s the measure of the third angle? What do you know about the length of a chord that subtends that angle. (Hint: all inscribed angles on the same side of this chord have the same measure — including the one whose vertex lies on its perpendicular bisector.)

Chris