When a arc or different congruent arcs the central angle an angle will be supplementary angles mAOB m2ACB 180 1 angle and circumscribed angle intercept the Solving for Unknown Measures What is the measure of angle D The arc intercepted by an inscribed angle is twice the measure of that angle TR B 43 x 2 86 The measure of the central angle is the same as the arc it intercepts m BOC 86 mz The circumscribed angle is supplementary to the central angle 180 m m AOB mZWYX ST W 43 0 X B CO www 180 B 86 D O