Core Connections Geometry, 2013
CC
Core Connections Geometry, 2013 View details
Chapter Closure

Exercise 125 Page 270

a We will deal with the questions one at a time.

i. These angles have corresponding positions with respect to the transversal. Therefore, these are corresponding angles. Since the lines cut by the transversal are parallel, we can use the Corresponding Angles Theorem and say that they are congruent. This means that the measures are equal.

ii. ∠ b and ∠ e are adjacent angles with a noncommon side that form opposite rays. This fits the description of a straight angle pair which means they are supplementary angles.

iii. The angles both lie between the two lines but on opposite sides of the transversal which makes them alternate interior angles. Because the lines cut by the transversal are parallel, we can use the Alternate Interior Angles Theorem and say that they are congruent. This means that the measures are equal.

iv. Each of the three angles occupy a vertex of a triangle. Therefore, by the Triangle Angle Sum Theorem, we know they sum to 180^(∘).

b Let's add the measure of ∠ c and ∠ e to the diagram.
i. Since ∠ j and ∠ e are corresponding angles, and the two lines cut by the transversal are parallel, we know by the Corresponding Angles Theorem that they are congruent. ∠ j ≅ ∠ e ⇒ m∠ j = 55^(∘)ii. Notice that ∠ c, ∠ d, and ∠ e form a straight angle. With this information, we can write an equation. 32^(∘)+m∠ d+55^(∘)=180^(∘) Let's solve for m∠ d.
32+m∠ d+55=180
87+m∠ d=180
m∠ d=93
The measure of ∠ d is 93^(∘).

iii. From the diagram, we see that ∠ a and ∠ e are vertical angles. Therefore, by the Vertical Angles Congruence Theorem, we know that they are congruent making the angle measures equal. ∠ a ≅ ∠ e ⇒ m∠ a = m∠ e iv. From the diagram, we see that m∠ g and m∠ c are alternate interior angles. Because the lines cut by the transversal are parallel, we can by the Alternative Interior Angles Theorem say that they are congruent. This means that the measures are equal. ∠ g ≅ ∠ c ⇒ m∠ g = m∠ c