1.l1=根号下2方加1.5方=2.5m l2=根号下3.6方加4.8方=6m tanδ1=1.5/2 δ1=37° tanδ2=4.8/3.6 δ2=53°
2.v=根号下4方加5方=根号下41m/s
3.略
4.行半周,180° 行10s 30°