33.(2022•陕西模拟)已知ΔABC\Delta ABCΔABC中,角AAA,BBB,CCC所对的边分别是aaa,bbb,ccc,且a=6a=6a=6,b=54cb=\frac{5}{4}cb=45c,A=2CA=2CA=2C,设OOO为ΔABC\Delta ABCΔABC的内心,则ΔAOB\Delta AOBΔAOB的面积为 ___7\sqrt{7}7___.