3.在同一平面内有直线a1,a2,a3,a4,…,a100,若a1⊥a2,a2∥a3,a3⊥a4,a4∥a5,…,按此规律进行下去,则a1与a100的位置关系是( )
| A. | 平行 | B. | 相交 | C. | 重合 | D. | 无法判断 |
2.
如图,P为直线l外一点,A、B、C在l上,且PB⊥l,下列说法中,正确的个数是( )
①PA、PB、PC三条线段中,PB最短;②线段PB的长叫做点P到直线l的距离;
③线段AB是点A到PB的距离;④线段AC的长是点A到PC的距离.
0 294055 294063 294069 294073 294079 294081 294085 294091 294093 294099 294105 294109 294111 294115 294121 294123 294129 294133 294135 294139 294141 294145 294147 294149 294150 294151 294153 294154 294155 294157 294159 294163 294165 294169 294171 294175 294181 294183 294189 294193 294195 294199 294205 294211 294213 294219 294223 294225 294231 294235 294241 294249 366461
①PA、PB、PC三条线段中,PB最短;②线段PB的长叫做点P到直线l的距离;
③线段AB是点A到PB的距离;④线段AC的长是点A到PC的距离.
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |