A survey drone is monitored from a fixed launch point. Its position relative to the launch point at time $t$ seconds is given by $r=\left(\begin{array}{c}9\\ -12\\ 20\end{array}\right)+t\left(\begin{array}{c}0.6\\ -0.8\\ 2.4\end{array}\right)$. The components represent easting (m), northing (m), and height above the launch point (m).

Two vertical communications towers, Tower $A$ and Tower $B$, stand on horizontal ground, with their bases $150$ m apart. From the top of Tower $A$, the angle of depression to the foot of Tower $B$ is $22^{\circ }$, and the angle of depression to the top of Tower $B$ is $8^{\circ }$.

A surveyor stands at a point $P$ on the ground such that the foot of Tower $A$, the foot of Tower $B$, and $P$ are collinear in that order, and $P$ is $100$ m from the foot of Tower $B$.

A bird flies in a straight line from the top of Tower $A$ to the top of Tower $B$.

A lighthouse $L$ stands on top of a vertical cliff. The foot of the cliff is at $F$, where $LF=45$ m. From the lighthouse, the keeper observes a boat $B$ on the sea below at an angle of depression of $18^{\circ }$. The points $F$, $B$ are on the same horizontal plane.

An airplane is flying at a constant altitude of $2000$ m above level ground. At time $t=0$, a radar station at point $R$ on the ground records the airplane at an angle of elevation of $32^{\circ }$. The airplane is flying in a straight line directly toward $R$ at a constant speed. $40$ seconds later, the radar records the airplane at an angle of elevation of $58^{\circ }$.

At a later time $T$, the radar records the airplane at an angle of elevation of $85^{\circ }$.