In the given figure, BA PARALLEL TO ED AND BC PARALLEL TO EF. SHOW THAT ANGLE ABC + ANGLE DEF =180 DEGREE
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Solution
If line FE is extended to join line AB at point G, angle FGB and angle ABC become supplementary angles because BC||EF = BC||GF. = angle FGB + angle ABC = 180° angle FGB = angle DEF since DE||AB and joined by line EG. Therefore, angle DEF + angle ABC = 180°.