3. and are equal perpendiculars to a line segment (see Fig.). Show that bisects .
In the given figure consider AOD and BOC.
(i) AD = BC (given)
(ii) A = B (given that the line AB is perpendicular to AD and BC)
(iii) AOD = BOC (vertically opposite angles).
Thus by AAS Postulate, we have
Hence by c.p.c.t. we can write :
And thus CD bisects AB.