拦水坝的横断面是梯形,已知坝顶宽3m,坝高4m,迎水坡长5m,背水坡的坡度比为i=1:
|
如图所示:
∵坝顶宽3m,坝高4m,迎水坡长5m,背水坡的坡度比为i=1:
,3
∴CD=3m,BC=5m,DE=4m,i=
=1:DE AE
,3
∴AE=
DE=3
×4=43
m,3
过CF⊥AB于点F,则CF=DE=4m,
在Rt△BCF中,BF=
=BC2-CF2
=3,52-42
∴AB=AE+EF+BF=4
+3+3=6+43
(m).3
故选C.
拦水坝的横断面是梯形,已知坝顶宽3m,坝高4m,迎水坡长5m,背水坡的坡度比为i=1:
|
如图所示:
∵坝顶宽3m,坝高4m,迎水坡长5m,背水坡的坡度比为i=1:
,3
∴CD=3m,BC=5m,DE=4m,i=
=1:DE AE
,3
∴AE=
DE=3
×4=43
m,3
过CF⊥AB于点F,则CF=DE=4m,
在Rt△BCF中,BF=
=BC2-CF2
=3,52-42
∴AB=AE+EF+BF=4
+3+3=6+43
(m).3
故选C.