Question

Part A

Answer 1

Definition: Vertical angles are the angles that are vertically opposite to each other when two lines intersect.

Vertical Angles Theorem: Vertical angles are congruent to each other.

Triangle Angle-Sum Theorem: The sum of the measures of the interior angles of a triangle is 180°.

The diagram shows triangle with to given angles. By the Triangle Angle-Sum Theorem you can find the measure of third angle. Angles x and y are vertical, then they are congruent.

Answer Part A: option A

By the Triangle Angle-Sum Theorem, x°+30°+70°=180°,

x°=80°

and

x°=y°=80°.

Answer part B: option B