(1)750s×cosav1=600s×v1
a=arccos4/5≈37°
(2)v2=120m/600s=0.2m/s
(3)你那个140m能用不?不用貌似做不出啊.
如果能用,(sinav1-v2)×750s=140m
v1就出来了.河宽也好求了.
(1)750s×cosav1=600s×v1
a=arccos4/5≈37°
(2)v2=120m/600s=0.2m/s
(3)你那个140m能用不?不用貌似做不出啊.
如果能用,(sinav1-v2)×750s=140m
v1就出来了.河宽也好求了.