An inscribed angle is half the measure of the arc it subtends. The converse of this is that the arc is twice the measure of the inscribed angle that subtends it.
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<h3>a)</h3>
Arc ADC is twice the measure of inscribed angle ABC, so is ...
Arc ADC = 2 × 135° = 270°
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<h3>b)</h3>
Angle DAE is half the measure of the arc it subtends, so is ...