CBSE|Arcs and Angles Subtended by them#!#RD Sharma Discussion of Ex.16.4

Any angle subtended by a minor arc in the alternate segment is acute and any angle subtended by a major arc in the alternate segment is obtuse.

Since the angles at the centre of a circle are proportional to the arcs subtending them (/_AOP)/(/_AOB)=(arc AP)/(arc APB)