Determine the measure of ZDAC Claim m DAC 18 degrees Reason Angle DAC is an interior angle formed by two tangents AD and AC so the interior angle has a measure equal to half the difference of the arcs AD and AC intercepts 70 40 18 O Claim m DAC 15 degrees Reason Angle DAC is an interior angle formed by two tangents AD and AC so the interior angle has a measure equal to half the difference of the arcs AD and AC intercepts 70 40 Claim m DAC 18 degrees Reason Angle DAC is an exterior angle formed by two secants AD and AC so the exterior angle has a measure equal to half the difference of the arcs AD and AC intercepts 70 40 18 Claim m DAC 15 degrees Reason Angle DAC is an exterior angle formed by two secants AD and AC so the exterior angle has a measure equal to half the difference of the arcs AD and AC intercepts 70 40 15