Fill in the blanks to make the statements true.

If sum of measures of two angles is 90°, then the angles are _________.

In Fig. 5.31, PQ||ST. Then, the value of x + y is

In Fig. 5.32, if PQ||RS and QR||TS, then the value a is

Fill in the blanks to make the statements true.

If the sum of measures of two angles is 180°, then they are _________.

Fill in the blanks to make the statements true.

A transversal intersects two or more than two lines at _________points.