每日小编都会为大家带来一些知识类的文章,那么今天小编为大家带来的是","title_text":"方面的消息知识,那么如果各位小伙伴感兴趣的话可以,认真的查阅一下下面的内容哦。
(1).【答案】
$left(1right)$见解析;$left(2right){60}^{circ }$;$left(3right)HF=dfrac{1}{2}CF$
【解析】
(1)$because triangle ABC$是等边三角形
$therefore AB=AC$,$angle ABC=angle BAC=angle ACB={60}^{circ }$
在$triangle ABD$和$triangle CAE$中
$left{begin{array}{l}AB=CA angle B=angle EAC BD=AEend{array}right.$
$therefore triangle ABDykcong triangle CAEleft(SASright)$
$therefore AD=CE$
(2)由(1)可知,$triangle ABDykcong triangle CAE$
$therefore angle BAD=angle ACE$
$because angle DFC$是$triangle ACF$的外角
$therefore angle DFC=angle FAC+angle ACE=angle FAC+angle BAD=angle BAC={60}^{circ }$
故$angle DFC= 60{}^{circ } $
(3)$because CHbot AD$
$therefore angle FHC= 90{}^{circ } $
$therefore triangle CFH$是直角三角形
由(2)可知,$ angle DFC={60}^{circ }$
$therefore angle FCH=180{}^{circ } - angle FHC- angle DFC = 180{}^{circ } -90{}^{circ }- 60{}^{circ } = {30}^{circ }$
$therefore HF=dfrac{1}{2}CF$
(2).【答案】
相等的边:$AB=BC=AC$,$CD=DE=CE$,$BD=AE$,$BM=AN$,$MD=NE$,$MC=MN=CN$
相等的角:$angle ABC=angle BAC=angle ACB=angle MCN=angle NMC=angle MNC=angle DCE=angle DEC=angle CDE={60}^{circ }$,$angle CAE=angle CBD$,$angle BDC=angle AEC$,$angle BCD=angle ACE$,$angle DMC=angle AMB=angle ENC=angle AND$,$angle BMC=angle AMD=angle ANC=angle DNE$
全等三角形:$triangle BCDykcong triangle ACE$,$triangle BCMykcong triangle ACN$,$triangle DCMykcong triangle ECN$
平行关系:$ABykparallel CD$,$ACykparallel DE$,$MNykparallel BE$
等边三角形:$triangle ABC$,$triangle DCE$,$triangle MCN$
【解析】
$because triangle ABC$和$triangle DCE$是等边三角形
$therefore AB=BC=AC$,$CD=DE=CE$,
$angle ABC=angle BAC=angle ACB={60}^{circ }$,$angle DCE=angle DEC=angle CDE={60}^{circ }$
$therefore angle ACB+angle MCN=angle DCE+angle MCN$
即$angle BCD=angle ACE$
在$triangle BCD$和$triangle ACE$中
$left{begin{array}{l}BC=AC angle BCD=angle ACE CD=CEend{array}right.$
$therefore triangle BCDykcong triangle ACE$$left(SASright)$
$therefore BD=AE$,$angle CAE=angle CBD$,$angle BDC=angle AEC$
$because angle MCN={180}^{circ }-angle ACB-angle DCE={60}^{circ }$
$therefore angle ACB=angle MCN=angle DCE={60}^{circ }$
在$triangle BCM$和$triangle ACN$中
$left{begin{array}{l}angle CBD=angle CAE BC=AC angle BCM=angle ACNend{array}right.$
$therefore triangle BCMykcong triangle ACN$$left(ASAright)$
$therefore MC=NC$,$BM=AN$,$angle BMC=angle ANC$
$therefore angle BMC=angle AMD=angle ANC=angle DNE$
同理$triangle DCMykcong triangle ECN$$left(ASAright)$
$therefore MD=NE$,$angle DMC=angle ENC$
$therefore angle DMC=angle AMB=angle ENC=angle AND$
$because MC=NC$,$angle MCN={60}^{circ }$
$therefore triangle MCN$为等边三角形
$therefore MC=MN=CN$,$angle MCN=angle CMN=angle CNM={60}^{circ }$
$therefore angle ABC=angle DCE={60}^{circ }$,$angle ACB=angle DEC={60}^{circ }$,$angle MNC=angle DCE={60}^{circ }$
$therefore ABykparallel CD$,$ACykparallel DE$,$MNykparallel BE$
本文到此结束,希望对大家有所帮助。