1
O - B
Time t
AB^2=A0^2+BO^2
Derivation of t
2AB dAB/dt=2AO dAO/dt+2BO dBO/dt
At 12: 30, ao =18-0.5 * 24 = 6bo =16 * 0.5 = 8ab =10.
dAO/dt=-24 dBO/dt= 16
You can get DAB/DT =- 1.6 by substitution.