Which reason supports the true statement that angle1 and angle8 are supplementary? m || n with transversal t

Angles 1 and 8 are created by line t intersecting with line m.

Line t is called a transversal line, because it intersects 2 parallel lines.

t divides the straight angle formed by m alone, forming the linear pair of angles (1) and (8), whose sum is 180 °, that is they are supplementary.

(1) and (8) are linear pairs

Because 1 and 8 are on a line and are a linear pair, that makes them supplementary. Linear pair definition is the reason.

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