Answer:
i havent done proofs in a while so i hope this makes sense? you should read over it and edit it if necessary.
i'm pretty sure it's supposed to be congruent triangles
1) AC bisects BD at O - given
2) AO=OC, DO=OB - def. of bisector (you can write these two seperately for both sides but don't think that's needed)
3) <AOB=<DOC - vertical angles
4) triangle AOB is congruent to triangle COD - SAS
5) <A is congruent to <C - CPCTC (corresponding parts of congruent triangles are congruent)
