Q89. Let ABC be a triangle of area $15 \sqrt { 2 }$ and the vectors $\overrightarrow { \mathrm { AB } } = \hat { i } + 2 \hat { j } - 7 \hat { k } , \overrightarrow { \mathrm { BC } } = \mathrm { a } \hat { i } + \mathrm { b } \hat { j } + \mathrm { ck }$ and $\overrightarrow { \mathrm { AC } } = 6 \hat { i } + \mathrm { d } \hat { j } - 2 \hat { k } , \mathrm {~d} > 0$. Then the square of the length of the largest side of the triangle ABC is $\_\_\_\_$\\