In Fig. 5.21, ∠AOC and ∠BOC form a pair of

Statements a and b are as given below:

a : If two lines intersect, then the vertically opposite angles are equal.

b : If a transversal intersects, two other lines, then the sum of two interior angles on the same side of the transversal is 180°.

Then

For Fig. 5.20, statements p and q are given below:

p : a and b are forming a linear pair.

q : a and b are forming a pair of adjacent angles.

Then,

In Fig. 5.22, the value of a is

In Fig. 5.23, if QP || SR, the value of a is