Big Ideas Math: Modeling Real Life, Grade 8
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Big Ideas Math: Modeling Real Life, Grade 8 View details
1. Parallel Lines and Transversals
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Exercise 32 Page 110

Practice makes perfect

We want to find the value of x. Let's take a look at the given figure.

Air Hockey Table
First we will find the value of m. We will use the fact that the two angles that measure m^(∘) and the angle that measures 64^(∘) are supplementary angles. This means that their measures add up to 180^(∘). m^(∘)+ 64^(∘)+ m^(∘)=180^(∘)Now we can solve for m.
m+64+m=180
Solve for m
m+m+64=180
2m+64=180
2m=116
m=58
Let's add this information to our figure.
Air Hockey Table

Next, notice that upper and lower edges of the table are parallel to each other. The distance that the puck travels from the lower to the upper edge is a transversal.

Air Hockey Table

We know that alternate interior angles are congruent if the transversal intersects parallel lines. Because of this, the sum of the angles that measure x^(∘) and 58^(∘) is equal to the sum of the angles that measure 64^(∘) and 58^(∘).

Air Hockey Table
With this, we can write the following equation. 58^(∘)+ x^(∘)= 64^(∘)+ 58^(∘) Let's solve it for x.
58+x=64+58
x=64
We found that the value of x is 64^(∘).
We want to find the relationship between two angles. One angle is the angle that the puck hits the edge of the table, let's call it a. The other is the angle the puck leaves the edge of the table, we can call it b.
Hockey puck hitting the edge
Now let's look at our diagram. We will focus on the point where the puck hits the edge for the second time.
Air Hockey Table

We can see that the measure of the angle that the puck hits the edge of the table is equal to the measure of the angle it leaves the edge of the table. This is true for any time the puck hits the edge of the table.