I say further that the angle of the greater segment, namely that contained by the circumference ABC and the straight line AC, is greater than a right angle;
and the angle of the less segment, namely that contained by the circumference ADC and the straight line AC, is less than a right angle.
This is at once manifest.
For, since the angle contained by the straight lines BA, AC is right,
the angle contained by the circumference ABC and the straight line AC is greater than a right angle.
Again, since the angle contained by the straight lines AC, AF is right,
the angle contained by the straight line CA and the circumference ADC is less than a right angle.