Cho tg ABC can tai A(<90).M la trung diem BC,tren tia doi cua tia MA lay diem K sao cho MA=MK.
a)C/m: tg AMB=tg KMC
b)C/m:AK vuong goc voi BC
c)Qua A ke duong thang vuong goc voi AK cat KC tai H.C/m:MK<CH
-Giup mik cau c voi m.n!!!
Những câu hỏi liên quan
cho tg abc vuong can tai a . m thuoc ac . goi i,k theo thu tu la trung diem bm,ac . qua a ke duong thang vuong goc voi ik . qua c ke duong thang vuong goc voi ac . chung cat nhau tai h c/m tg mch vuong can
cho tg abc vuong can tai a . m thuoc ac . goi i,k theo thu tu la trung diem bm,ac . qua a ke duong thang vuong goc voi ik . qua c ke duong thang vuong goc voi ac . chung cat nhau tai h c/m tg mch vuong can
bai1:cho tam giac abc vuong can tai a. 1 duong thang di qua a khong cat doan bc. bh vuong d,ckvuongd. cmr ah=ck
bai2: cho tg abc vuong tai a. phan giac bd,ce cat tai o.
a,goc boc=?
b,lay m,n thuoc bc s cho bm=ba,cn=ca.cm dm//en
c,goi giao diem an va bd la i.cm tg aim vuong can
giup minh voi. cam on a!
cho tg ABC co ba goc nhon . duong cao BE, CF cat nhau tai O. duong tron tam O duong kinh AB cat CF tai M. duong tron tam O duong kinh AC cat BE tai N. CM: tg AMN can
Cho tam giac ABC can tai A ( AB>AC) lay M la trung diem BC Chung Minh
a) BAM^=CAM^
b) tia phan giac cua goc ABC cat Am tai H. Chung Minh BH=CH
c) Duong thang di qua A song song voi BC cat BH tai I chung Minh tg ACI can
cho tg ABC co ba goc nhon . duong cao BE, CF . duong tron tam O duong kinh AB cat CF tai M. duong tron tam O' duong kinh AC cat BE tai N. CM: tg AMN can
Cho tg ABC can tai A(<90).M la trung diem BC,tren tia doi cua tia MA lay diem K sao cho MA=MK.
a)C/m: tg AMB=tg KMC
b)C/m:AK vuong goc voi BC
c)Qua A ke duong thang vuong goc voi AK cat KC tai H.C/m:MK<CH
-Giup mik cau c voi m.n!!!
Cho tg ABC can tai A (A<900) . Ke BH vuong goc vs AC, CKvuong goc vs AB. Goi M la giao diem cua BH va CK
a,CM tg HAB=tg KAC
b,CM:KH//BC
c,Goi N la trung diem cua BC. Chứng minh A,M,Nthang hàng
a, Xet tg vuong HAB va tg vuong KAC co:
AB=AC(hai canh ben tg can ABC)
BAC chung
Do do tg vuong HAB=tg vuong HAC(ch-gn)
b,Vi tg HAB=tg KAC (cau a)
=>HA=KA(2 canh t/u)
Xet tg AKH co :
HA=KA(cmt)
=>tg HAK can tai A(d/n tg can)
=>AKH= \(\dfrac{180^0-BAC}{2}\) (1)
Vi tg ABC can tai A :
=> ABC= \(\dfrac{180^0-BAC}{2}\) (2)
Tu (1) va (2)
=> AKH =ABC mà 2 góc này ở vị trí hai góc đồng vị
=>KH//BC(dpcm)
c, Xet tg vuong AKM va tg vuong AMH co:
AM chung
KA=AH(cau a)
do do :tg vuong KAM=tg vuong HAM(ch-gn)
=>KAM=HAM(2 goc t/u)
Ma tia AMnam giua hai tia KAva AH
=>AM la tia phan giac KAH (3)
Xet tg BAMva tg ACN co:
AB=AC(2 canh ben tg ABC can)
ABC=ACB(2 goc o day tg can ABC)
BN=CN(N la td BC)
Do do tg ABN=tg ACN(c.g.c)
=>BAN=NAC(2 goc t/u)
Ma tia AN nam giua hai tia AB va AC
=> AN la tia p/g BAC (4)
Tu (3) va (4)
=>3 diem A,M,N thang hang
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cho tg ABC vuong tai A, duong cao AH
1)cm: AH2=HB.HC
2) goi D la diem doi xung cua B qua H.. E la hinh chieu vuong goc cua D tren AC. CM: tg AHE can
3)F la trung diem cua HC, N la diem doi xung cua A qua H. Duong thang di qua H vuong goc voi AF cat AB tai M. CM: MN song song BC