Question

please solve this problem.

Answer 1

In ΔAOB, 
AB=10cm. OB=1/2(BD)=8cm. OA=1/2(AC)=6cm. [Diagonals of a ||gram bisect each other.]
ar(AOB)=$\sqrt{s(s-a)(s-b)(s-c)}$
=48$\sqrt{21}$ cm²