如图，⊙O是△ABC的外接圆，AC是直径，过点O作OD⊥AB于点D，延长DO交⊙O于点P，过点P作PE⊥AC于点E，作射线DE交BC的延长线于F点，连接PF．（1）若∠POC=60°，AC=12，求劣弧PC的长；（结果保留π）（2）求证：O-题库-e学大
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如图，⊙O是△ABC的外接圆，AC是直径，过点O作OD⊥AB于点D，延长DO交⊙O于点P，过点P作PE⊥AC于点E，作射线DE交BC的延长线于F点，连接PF．（1）若∠POC=60°，AC=12，求劣弧PC的长；（结果保留π）（2）求证：O-题库-e学大
【解答题】如图，⊙O是△ABC的外接圆，AC是直径，过点O作OD⊥AB于点D，延长DO交⊙O于点P，过点P作PE⊥AC于点E，作射线DE交BC的延长线于F点，连接PF．（1）若∠POC=60°，AC=12，求劣弧PC的长；（结果保留π）（2）求证：OD=OE；（3）求证：PF是⊙O的切线．（1）解：∵AC=12，∴CO=6，∴==2π；（2）证明：∵PE⊥AC，OD⊥AB，∠PEA=90°，∠ADO=90°在△ADO和△PEO中，，∴△POE≌△AOD（AAS），∴OD=EO；（3）证明：如图，连接AP，PC，∵OA=OP，∴∠OAP=∠OPA，由（1）得OD=EO，∴∠ODE=∠OED，又∵∠AOP=∠EOD，∴∠OPA=∠ODE，∴AP∥DF，∵AC是直径，∴∠APC=90°，∴∠PQE=90°∴PC⊥EF，又∵DP∥BF，∴∠ODE=∠EFC，∵∠OED=∠CEF，∴∠CEF=∠EFC，∴CE=CF，∴PC为EF的中垂线，∴∠EPQ=∠QPF，∵△CEP∽△CAP∴∠EPQ=∠EAP，∴∠QPF=∠EAP，∴∠QPF=∠OPA，∵∠OPA+∠OPC=90°，∴∠QPF+∠OPC=90°，∴OP⊥PF，∴PF是⊙O的切线．答案解析相关微课程上一题：下一题：发现相似题
学生端下载autotools - possibly undefined macro: AC_MSG_ERROR - Stack Overflow
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I have the following in configure.ac:
AC_CHECK_PROGS(MAKE,$MAKE make gmake,error)
if test "x$MAKE" = "xerror" ;then
AC_MSG_ERROR([cannot find a make command])
This has been in our project for a long time, but in some set ups, I get this error:
configure.ac:45: error: possibly undefined macro: AC_MSG_ERROR
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
The lines that were recently added above this:
AC_CONFIG_MACRO_DIR([m4])
Can anyone explain what causes this error and how to track down the problem?
EDIT: Adding details about the differences.
Box that works:
uname -a Linux host1 2.6.38-13-generic #53-Ubuntu SMP Mon Nov 28 19:33:45 UTC
x86_64 x86_64 GNU/Linux
automake: 1.11.1
autoconf: 2.67
m4: 1.4.14
libtoolize: 2.2.6b
Box that doesn't work:
Linux host2 2.6.32-35-generic-pae #78-Ubuntu SMP Tue Oct 11 17:01:12 UTC
automake: 1.11.1
autoconf: 2.65
m4: 1.4.13
libtoolize: 2.2.6b
NEW EDIT: only 32 bit machines experience this difficulty.
UPDATED I am able to reproduce the problem on a CentOS machine with autoconf 2.67, automake 1.11.1, libtool 2.2.6b, and m4 1.4.14. Is this just a bug with 32-bit machines?
6,03262342
4,40622141
I had this same issue and found that pkg-config package was missing.
After installing the package, everything generated correctly.
It is recommended to use autoreconf -fi instead of manually calling
#and whatever else to properly populate aclocal.m4 and so on.
Adding ACLOCAL_AMFLAGS = -I m4 (to the toplevel Makefile.am) and AC_CONFIG_MACRO_DIR([m4]) is currently still optional if you do not use any own m4 files, but of course, doing it will silence the proocess :)
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I had this problem with my own configure.ac, but in this case (and for the benefit of anyone here from Google) it was because I had accidentally quoted the AC_MSG_ERROR so it was being treated as a string:
AX_BOOST_BASE([1.42], [], [AC_MSG_ERROR([Could not find Boost])])
Once I removed the square brackets around the AC_MSG_ERROR macro, it worked:
AX_BOOST_BASE([1.42], [], AC_MSG_ERROR([Could not find Boost]))
Those comments saying you should install pkg-config or some package are missing the point.
The AC_MSG_ERROR is supposed to work and give you a helpful message like "You need to install package XYZ", but because of some problem, the AC_MSG_ERROR doesn't work.
Installing package XYZ will certainly make the error go away, but only because once the package is there, there is no longer any need to print an error message!
So installing pkg-config or a particular package just bypasses the problem, it doesn't actually fix it.
8,98366289
I have experienced this same problem under CentOS 7
In may case, the problem went off after installation of libcurl-devel (libcurl was already installed on this machine)
6,48312231
i also had similar problem.. my solution is to
apt-get install libcurl4-openssl-dev
(i had libcurl allready installed )
worked for me at least..
Are you setting up a local 'm4' directory? e.g.,
& aclocal -I m4 --install
Some packages come with an autogen.sh or initgen.sh shell script to run glibtoolize, autoheader, autoconf, automake. Here's an autogen.sh script I use:
#! /bin/sh
case `uname` in Darwin*) glibtoolize --;
*) libtoolize --; esac
autoheader
aclocal -I m4 --install
automake --foreign --add-missing --force-missing --copy
You may need to add ACLOCAL_AMFLAGS = -I m4 to the top-level Makefile.am.
16.2k12966
The error is generated by autom4te.
If things are set up correctly, the portion of the code that generates that error should never see 'AC_MSG_ERROR', because it should have been expanded by m4 before that point.
You say the error only happens "in some setups".
I would suggest that in those setups, your autoconf installation is fubar.
Possibly you have an incompatible version of m4 installed.
118k29193223
Using MacOS X
sudo port install pkgconfig
was the solution!
On Mac OS X el captain with brew, try:
brew install pkgconfig
This worked for me.
I solved this by yum install libtool
For Debian.
Required packages are:
m4 automake pkg-config libtool
This happened to me when I forgot a , in the arguments for a locally defined macro.
Spent hours trying to figure it out (barely acquainted with autotools)...
AC_CHECK_MACRO([Foo]
AC_LOCAL_DO([......
should have been
AC_CHECK_MACRO([Foo],
# &-- Notice comma, doh!
AC_LOCAL_DO([......
Seems like it should have given me an error or such, but I suppose being a macro processor it can only do what its told.
I had the same problem on Ubuntu (error: possibly undefined macro: AC_MSG_ERROR) but the answers above didn't work for me. I found the solution
That did the trick:
$ LANG=C LC_CTYPE=C ./autogen.sh
My issue is resolved after I install pkg-config on Mac (brew install pkg-config)
There are two possible reasons for that problem:
did not install aclocal.
solution：install libtool
For ubuntu: sudo apt-get install libtool
For centos: sudo yum install libtool
the path to LIBTOOL.m4 is error.
use aclocal --print-ac-dir to check current path to aclocal.(It's usually should be "/usr/share/aclocal" or "/usr/share/aclocal")
Then check if there are *.m4 files.
If not, cp corresponding *.m4 files to this path.( Maybe cp /usr/share/aclocal/*.m4 /usr/local/share/aclocal/ or cp /usr/local/share/aclocal/*.m4 /usr/share/aclocal/)
Hope it helps
I had the same problem with the Macports port "openocd" (locally modified the Portfile to use the git repository) on a freshly installed machine.
The permanent fix is easy, define a dependency to pkgconfig in the Portfile:
depends_lib-append
port:pkgconfig
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如图已知ac与bd交于点o,ad平行bc且ad=dc,你能说明bo=do吗?
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不能,条件不足,不能证明bo=do.而且可以画出满足ac与bd交于点o,ad平行bc且ad=dc条件,但bo不等于do的图形,故而不能证明bo=do.
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p>具体封装尺寸请见图.com/zhidao/pic/item/b17eca810ccd9a444ad.jpg" target="_blank" title="点击查看大图" class="ikqb_img_alink"><img class="ikqb_img" src="http.baidu.jpg" esrc="http。<a href="http.hiphotos.baidu.com/zhidao/wh%3D450%2C600/sign=10ebe73ab43533faf5e39b2a9de3d129/b17eca810ccd9a444ad://b.baidu，如下为VISHAY例，各品牌也许会略有差异
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我们会通过消息、邮箱等方式尽快将举报结果通知您。如图所示，AB与CD相交于点O，且AO=BO，CO=DO，过点O作直线EF交AC于E，交BD于F，试说明OE=OF_百度知道
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wordWrap:normal"><div style="background-image，∴∠A=∠B，在△AOE和△OBF中，，∴△AOE≌△OBF．∴OE=OF．; background-attachment: background-origin: initial: hidden: url('http://wordSpacing: 9 overflow-x: overflow-y: height: 22.5 background-position: background-repeat: no- " muststretch="v">∠AOC＝∠BODCO＝DO，∴△AOC≌△BOD: no-repeat repeat.baidu:hidden">AO＝BO<td style="padding-top
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