Question

Question 9
In the figure, which of the two lines are parallel and why?

Answer 1

In the first figure, sum of two interior angles ${132}^{\circ }+{48}^{\circ }={180}^{\circ }$
Here, we see that the sum of two interior angles on the same side of n is ${180}^{\circ }$.
Therefore, they are parallel lines.
In the second figure,
the sum of two interior angles ${73}^{\circ }+{106}^{\circ }={179}^{\circ }\ne {180}^{\circ }$.
Here, we see that the sum of two interior angles on the same side of r is not equal to ${180}^{\circ }$.
Therefore, they are not parallel lines.