Aob= 120。
So aoc=60
Ao = co in triangular aoc
So oac=60
Aob= 120。
So ac//ob
Similarly, oa//bc and oacb are parallelograms.
oa=ob
So oacb is a diamond.
Question 2: apc=bpc, ac=bc.
The triangle acb is isosceles.
Apb= 120。
So acb=60
So acb is equilateral.