[填空题]
The diagram below sh ehc70kkd(p .avegic+i0+2uy7kf dc+ ows a triangle ABC. The size of angle $\mathrm{A}\hat{\mathrm{M}}\mathrm{C}$ is $150^{\circ}$, where M is the midpoint of AB. MBC is an isosceles triangle, with MC = MB = 4 cm.
1.Write down the length of AM. cm
2.Find the size of angle $\textrm{C}\hat{\textrm{M}}\textrm{B}$. $^{\circ}$
3.Find the size of angle $\textrm{A}\hat{\textrm{B}}\textrm{C}$. $^{\circ}$
4.Find the length of CB. cm
