Prove that the straight lines perpendicular to the same straight line are parallel to one another.

Let AB and CD perpendicular to the line MN

ABD = 90o(Since, AB perpendicular MN) (i)


CON = 90o(Since, CD perpendicular MN) (ii)


Now,


ABD = CON = 90o


Therefore,


AB CD (Since, corresponding angles are equal)


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