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Вопрос по алгебре:
3.Отрезки АВ и CD равны и пересекаются в точке О так, АО = OD. Докажите, что BD = АС.-
Автор:
mendez
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Ответ:
АВ=СD ( по условию) , АО=СD ( тоже по услов.) следовательно СО=ОВ
потом
AB=CD ( по услов) углы AOC=BOD (т.к вертикальные) СО=ОВ из этого следует .что треугольники AOC=BOD ( по первому признаку равенства) раз треугольники равны, следовательно ВD=AC
Ответ:
Если это треугольники:
Дано:Отрезки AB, CD
AO=OD
Доказать:BD = AC
Решение:1.АВ=СД(по усл),АО=СД(по усл) => СО=ОВ
2.АВ=СД(по усл) СО=ОВ(по доказ.), => АОС=ДОВ(по первому признаку) => АС=ДВ
ЧТД
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