In the diagram, minor arc AB : minor arc BC : major arc CA = 1 : 3 : 6. What is angle ABC in degrees?
∠AOB = 1* (360 / 10) = 36º
∠BOC = 3* (360 / 10) = 102º
Let M and N be the midpoints of line segments AB and BC.
∠MBO = 1/2 (180 - 36) = 72º
∠NBO = 1/2 (180 - 102) = 39º
∠ABC = 72º + 39º = 111º
