Exercise 4 Page 181

Two lines are parallel if their slopes are identical. For this exercise, we have been given two points on each line, so we have enough information to calculate their slopes using the Slope Formula. m=y_2- y_1/x_2- x_1Note that when choosing points to substitute for ( x_1, y_1) and ( x_2, y_2), it does not matter which points on the line you choose, since the result will be the same. Let's start with line a, which passes through ( 0, 5) and ( 2, 0).

We will use a similar method to identify the slopes of lines b and c.

Now that we have identified the slope of each line, we can see that b and c have the same slope, so we know that they are parallel.