三角形的外心是（）A．三条中线的交点B．三个内角的角平分线的交点C．三条边的垂直平分线的交点D．三条高的交点-数学

更多内容推荐

• 若△ABC的周长为20cm，面积为32cm2，则△ABC的内切圆半径为______．-数学
• 已知，△ABC中，∠C=90°，G是三角形的重心，AB=8，求：①线段GC的长；②过点G的直线MN∥AB，交AC于M，BC于N，求MN的长．-数学
• 等边△ABC的边长为2cm，则它的外接圆的半径为______cm，内切圆的半径为______cm．-数学
• 已知Rt△ABC外接圆半径为R，内切圆半径为r，则△ABC的周长为（）。-九年级数学
• 如图，已知△ABC的中线BD、CE相交于点O，如果BD=6，那么OD=______．-数学
• 如图所示，四边形ABCD为一正方形，E、F分别为BC、CD的中点，对角线AC与BD相交于O点，且AE与OB相交于G点，AF与OD相交于H点，下列说法正确的有①E点是线段BC的重心；②G点是△ABC-八
• 如图a所示，有一质地均匀的三角形铁片，其中一中线AD长24cm，若阿龙想用食指撑住此铁片，如图b，则支撑点应设在距离D点（）cm处最恰当。-八年级数学
• 如图，⊙O是△ABC的内切圆，与边BC，CA，AB的切点分别为D，E，F，若∠A=70°，则∠EDF=（）度．-九年级数学
• 如图所示，在△ABC中，AB=AC，G是△ABC的重心，过G点作GD⊥AB，GE⊥AC，垂足为D，E。（1）猜想：GD___GE；（2）试对上面的猜想加以证明。-八年级数学
• （1）已知点G是△ABC的重心，AG=6，那么DG=___，点G与边BC中点之间的距离是____；（2）△ABC的面积为9cm2，则△ABG的面积为___cm2。（3）连接CG，若AG⊥GC，AC=4
• 在边长为5cm、12cm、13cm的三角形白铁皮上剪下一个最大的圆，此圆的半径为（）。-九年级数学
• 已知△ABC的内切圆⊙O如图，若∠DEF=54°，则∠BAC等于[]A.96°B.48°C.24°D.72°-九年级数学
• 已知在△ABC中，AB=AC=13，BC=10，那么△ABC的内切圆的半径为[]A.B.C.2D.3-九年级数学
• 和三角形三个顶点的距离相等的点是[]A．三条角平分线的交点B．三边中线的交点C．三边上高所在直线的交点D．三边的垂直平分线的交点-八年级数学
• 边长为6的正三角形的外接圆和内切圆的半径分别为______．-数学
• 三角形的内心到三角形______的距离相等．-数学
• 一个三角形的外心与内心恰好重合，这个三角形是______．-数学
• 已知，⊙O是△ABC的外接圆，若AC=5，且∠ABC=30°，则⊙O的面积为（）．-九年级数学
• One evening in February 2007, a student named Paula Ceely brought her car to a stop on a remote road
• People aren’t walking any more---if they can figure out a way to avoid it.I felt superior about this
• Microsoft founder Bill Gates has opened up about being a parent，stating that 13 is an appropriate ag
• Dogs and cats are not for students who live in the dormitory. Just think about the noise, the smell
• America’s Beauty Is in Its Diversity America is built on the idea of freedom, and there is no except
• Flight cancellations(取消) and loss of luggage can ruin even the best-planned holiday. The key to a st
• 根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。小题1:When a person does a certain thing over and over again,
• However urban life strikes you，cities worldwide have been growing even more rapidly．Some of this gro
• Everywhere I look outside my home I see people busy on their high-tech devices, while driving, walki
• It was the end of my first day as waitress in a busy New York restaurant.My cap had gone away，and my
• Two years ago, Shirley, wife, mother and doctor, found herself worn out. She got up earlier, and wen
• Comment on CRIHere are the comments on CRI (China Radio International) given by people from differen
• My son starts school today. It's going to be and new to him for a while. And I wish you would s
• "Efficiency is the by-product of comfort," says Dr. Erwin Tichauer of New York University.
• It was August 2nd,1927.The news had spread fast.A man named Ralph Peer was coming to the city of Bri
• Thank you for trusting me. I enjoy exchanging my ideas with yoursThe first thing I want to tell you
• Ever wonder how this season’s celebrations affect the environment? Guest blogger Krista Fairles take
• Traveling can be a fun way to gain life experiences, especially during Spring Break — a week-long s
• Have you got a Facebook account? Are you thinking of getting one? Jamie Simmonds has just signed up.
• We all know what it is like to be unable to turn your head because of a cold in the muscles of your
• Our Future HomesWhat kinds of homes will we live the future? Nobody can be sure, architects, and sci
• Tears slid down Ken's cheeks. Their newbom baby was removed from life supprt, taken back to her
• It might have been a really bad stressful day, feeling trapped inside by the cold and snow which sur
• 小题1:Where did Li Hua see Mrs Daniels’ advertisement?A．At London University.B．In a newspaperC．On the
• As a child, I was afraid of everything. At the age of 8, I even became 1 of getting Halloween candy.
• One afternoon, many years ago, I went to pick up my mother from work. I got there a little early so
• Scientists find that hard-working people live longer than average men and women. Career women are__1
• Ben and his wife Susan were on their way to have dinner with their friends. It was a dark，windy nigh
• Summer school is something a kid will never forget．For some, it's a way to advance past their c
• There have been discussions about retire age limit recently. Does it make sense to make people retir
• In this modern world, we rush around all day, doing things, talking, emailing, sending and reading m
• Visiting London can be an expensive trip, so establishing a budget and finding bargains when you arr