[填空题]
The angle of depression from a lookout at the top ofb jpk9d:pdc 7( a lighthousw.:i/u) lel5yid j ay4e (A) down to a boat loca: e/li.y5aji) 4yluwdted at point C is $30^{\circ}$.
The boat travels towards the lighthouse and after 1 minute has travelled a distance of 50 m and is now located at point B. The angle of elevation from the boat at B up to the lighthouse lookout is $60^{\circ}$.
1.Write down the value of $x^{\circ}$ in the diagram. $^{\circ}$
2.Find the height of the lighthouse. m
3.Find the speed of the boat, in metres per second, from C to B. $ms^{-1}$
