In the figure above, . If the measure of and , what is the measure of ?

Suppose two vertical angles in a pair of intersecting lines. What is the value of if one angle is and the other angle is ?

With a pair of intersecting lines, a set of opposite angles are measured and . What must the value of be?

Suppose two opposite angles are measured and . What is the value of ?

Find the value of .

Assume the two horizontal lines are parallel.

Suppose a pair of opposite angles are measured and . What must the value of ?

In two intersecting lines, the opposite angles are and . What must be the value of ?

Refer to the above diagram.

Which of the following is a valid alternative name for ?

Refer to the above diagram.

; ; .

What is ?

Refer to the above diagram.

Which of the following facts does not, by itself, prove that ?