Page 211 - ABCTE Study Guide_Neat

Question

What is the measure of the angle that is supplementary to 2 above?

A 35°

B 45°

C 125°

D 135°

Answer

The correct answer choice is C. Two angles are supplementary if the sum of their measures is 180°. So
the angle that is supplementary to 2 measures 180°- 55°, or 125°. Choice A is incorrect. An angle that
measures 35° is complementary to 2.

Recall that two lines are parallel if the distance between them is constant. That is, the distance stays the
same. Also recall that perpendicular lines form right angles. There are marks in the figure below that show

lines and are parallel. The right angle symbol shows lines and are perpendicular.

What can you conclude about lines and ? If two lines are parallel, and one of these lines is
perpendicular to a third line, then the other parallel line is also perpendicular to the third line. That means

that and are perpendicular.

In the figure above, ABC and DBF are vertical angles. Pairs of vertical angles are formed where
two lines intersect. GFH and BFE are also vertical angles. Can you find two other pairs of vertical
angles in the figure?

Vertical angles are congruent. That means that they have the same measure. We know that
ABC and DBF are vertical angles, and ABC is a right angle, so we can conclude that DBF =
90°.