Answer the following questions on the basic idea of a segment in a circle:
a. (i) Define a sector and a segment of a circle.
b. (ii) List, in logical order, the steps you would follow to calculate the area of a minor segment that subtends an angle of 120° at the centre of a circle of radius r. Do not carry out any numerical calculation; only state the sequence of operations together with the expressions involved.
c. (iii) Give a clear reason why the area of the triangle formed by the two radii is subtracted and not added when finding the area of a segment.