![](http://hiphotos.baidu.com/zhidao/pic/item/810a19d8bc3eb1359fb27d0da51ea8d3fd1f440b.jpg)
∵A點(diǎn)經(jīng)過點(diǎn)C反射后經(jīng)過B點(diǎn),
∴∠OCA=∠DCB,
∴△OAC∽△DBC,
又∵BD⊥CD,AO⊥OC,根據(jù)勾股定理得出
OA |
DB |
AC |
BC |
OC |
CD |
OA |
DB |
AC |
BC |
OC |
CD |
1 |
3 |
∵OD=OC+CD=6
∴OC=6×
1 |
4 |
AC=
OA2+OC2 |
22+1.52 |
BC=2.5×3=7.5,
AC+BC=2.5+7.5=10;
法2:延長BC,與y軸交于E點(diǎn),過B作BF⊥y軸,交y軸于F點(diǎn),
由題意得到A與E關(guān)于x軸對稱,可得E(0,-2),AC=CE,
∴BF=6,EF=OE+OF=6+2=8,
在Rt△BEF中,根據(jù)勾股定理得:BE=
BF2+EF2 |
則光線從A到B所經(jīng)過的路程為AC+CB=EC+CB=BE=10.
故選A