【简答题】如图,已知△ABC中,∠C=90°,∠B=60°,AC=4,等边△DEF的一边在直角边AC上移动,当点E与点C重合时,点D恰好落在AB边上, (1)求等边△DEF的边长; (2)请你探索,在移动过程中,线段CE与图中哪条线段始终保持相等,并说明理由; (3)若设线段CE为x,在移动过程中,等边△DEF与Rt△ABC两图形重叠部分的面积为y.请你写出y与x的函数关系式,并写出自变量x的取值范围.
【简答题】如图,在△ABC中,D是BC边上的点(不与点B、C重合),连结AD. 问题引入: (1)如图①,当点D是BC边上的中点时,S △ ABD :S △ ABC = ;当点D是BC边上任意一点时,S △ ABD :S △ ABC = (用图中已有线段表示). 探索研究: (2)如图②,在△ABC中,O点是线段AD上一点(不与点A、D重合),连结BO、CO,试猜想S △ BOC 与S △ ABC 之比应该...
【简答题】Traveling by train is usually not easy in China. It can be hard to get a ticket. When you’re traveling to the railway station, you look at your watch, for you are afraid you will miss your train. But ...
【单选题】如图,已知△ABC中,∠CAB=∠B=30°,AB=2 3 ,点D在BC边上,把△ABC沿AD翻折使AB与AC重合,得△AB′D,则△ABC与△AB′D重叠部分的面积为( )
【单选题】如图,点D为△ABC边AB的中点,将△ABC沿经过点D的直线折叠,使点A刚好落在BC边上的点F处,若∠B=46°,则∠BDF的度数为( )
【简答题】如图1,在△ABC中,D、E、F分别为三边的中点,在边AB上,△BDG与四边形ACDG的周长相等,设BC=a、AC=b、AB=c, (1)求线段BG的长; (2)求证:DG平分∠EDF; (3)连接CG,如图2,若△BDG与△DFG相似,求证:BG⊥CG。
【简答题】Traveling by train is usually not easy in China. It can be hard to get a ticket. When you’re traveling to the railway station you look at your watch, afraid you will miss your train. But there is good...
【单选题】Train as hard as you can ____ you’ll win the swimming competition.
【简答题】如图,已知点D是△ABC的边BC(不含点B,C)上的一点,DE ∥ AB交AC于点E,DF ∥ AC交AB于点F、要使四边形AFDE是矩形,则在△ABC中要增加的一个条件是:______.
【简答题】如图1,在△ABC中,D、E、F分别为三边的中点,在边AB上,△BDG与四边形ACDG的周长相等,设BC=a、AC=b、AB=c. (1)求线段BG的长; (2)求证:DG平分∠EDF; (3)连接CG,如图2,若△BDG与△DFG相似,求证:BG⊥CG.