Given:
The coordinates of the points are B(-4,3), G(-2, 4), H(1, -2), L(-1, -3).
To find:
Whether GL and BH are parallel or not by using their slopes.
Solution:
If a line passes through the two points, then the slope of the line is

Using the slope formula, the slope of GL is




Using the slope formula, the slope of BH is




We know that slopes of parallel lines are always equal.
The slopes of GL and BH are -7 and -1 respectively but they are not equal, therefore GL and BH are not parallel lines.