$$15 \cdot ( 2 ) \sqrt { 4 ^ { 2 } + 6 ^ { 2 } - 72 b } = \frac { 1 } { 3 } ( ( a + 1 ) ) = \frac { 1 } { 2 } ( \sqrt { 2 } + 16 \sqrt { 2 } )$$
$60\sqrt{13-18b}=\frac{a+1}{3}\text{ and }a=\frac{51\sqrt{2}}{2}-1$
$b=\frac{93311}{129600}\approx 0.719992284$
$a=\frac{51\sqrt{2}}{2}-1$
$a=\frac{51\sqrt{2}}{2}-1$
$b = \frac{93311}{129600} = 0.7199922839506173$
