Q24的精選

問題詳情：已知直線l過點(1,1),過點P(-1,3)作直線m⊥l,垂足爲M,則點M到點Q(2,4)距離的取值範圍爲. 【回答】[,3]解析直線l過定點設爲A,則有A(1,1),設M(x,y),因爲直線m⊥l,則,所以=0,即(-1-x,3-y)·(1-x,1-y)=0,化簡爲:...