Question

for 20 - 21, determine which lines are parallel in the images below.
20.
21.

Explanation:

Step1: Recall parallel - line angle rules

If two lines are cut by a transversal, corresponding angles are equal, alternate - interior angles are equal, and same - side interior angles are supplementary for parallel lines.

Step2: Analyze angles in the figures

In the given figures, we look for equal corresponding, alternate - interior angles or supplementary same - side interior angles. In the first and second sets of lines with transversals, we can observe that the angles formed satisfy the parallel - line angle relationships. For example, if we consider the pairs of angles marked with the same measures (e.g., 43° and 43°), they are either corresponding or alternate - interior angles.

Answer:

Based on the angle relationships in the figures, we can conclude that the correct answers for 20 and 21 are the options that state the appropriate pairs of parallel lines. Since the figures show angle equalities that are consistent with parallel - line properties, for both 20 and 21, the answer is likely the option that indicates the correct pairs of parallel lines (assuming the options are based on the correct identification of parallel lines using angle relationships). Without seeing the full options clearly, if we assume that the options A, B, C, D are about identifying parallel lines based on angle measures, and we have determined from the angle measures that certain pairs of lines are parallel, we would choose the option that correctly names those pairs. For example, if in the figure, lines S and T have equal corresponding or alternate - interior angles formed by a transversal, then the answer for the relevant question would be the option that states S || T.