In the context of parallel lines and angle relationships, let's evaluate each statement:
A. True. Supplementary angles are angles whose measures add up to 180°. For example, if one angle measures 120°, the other angle would need to measure 60° to be supplementary.
B. True. Adjacent angles that form a line are supplementary. When two adjacent angles form a straight line, their measures add up to 180°.
C. False. Supplementary angles are not always congruent. Congruent angles have the same measure, while supplementary angles only add up to 180°.
D. False. Supplementary angles are not always opposite each other. They can be adjacent angles that form a straight line, not necessarily opposite each other.
E. False. Supplementary angles are angles whose measures add up to 180°, not 90°. If angles add up to 90°, they are known as complementary angles.
Therefore, the true statements from the options provided are A and B.
