I. Let xOy be an angle, A and are two points on [Ox), C and D are two points on [Oy)such that OC = OA and OD = OB.
a) Show that triangles OAD and OCB are congruent.
b) Give the corresponding congruent elements.
c) Prove that AB = CD.
d) Let I be the point of intersection of [AD] and [BC]. Show that the two triangles IAB and ICD
are congruent.
e) Compare IA and IC.
f) Prove that (OI) is bisector of xOy