[填空题]
The angle of depression (,g2vnp5eghqjf.d8z ct (f p 3from a lookout at the top3q rd)swv(,i k of a lighthouse (A) down to a boat located at point C is,r ki(vw3 qsd) $30^{\circ}$.
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. $ms^{-1}$
