Cho tam giac ABC. Ve trung tuyen BM. Tren tia BM lay 2 diem G va K sao cho BG=\(\dfrac{2}{3}\)BM va G la trung diem cua BK. Goi N la trung diem cua KC, GN cat CM tai O. CM ;
a. Goc O la trong tam cua tam giac GAC
b.GO=\(\dfrac{1}{3}\) BC
Những câu hỏi liên quan
Cho tam giac abc co ab<ac goi m la trung diem cua bc tren tia am lay diem d sao cho n la trung diem cua ad
Cm: tam giac abm= tam giac dcmCm ab//dc va so sanh goc mab va goc macTren doan thang am lay g sao cho ag=2gm tai bg cat ac tai n tia cg cat ab tai p.Cm am+bn+cp>3/4(ab+ac+bc)
bai 3 ; cho tam giac abc . tren canh ab lay diem m , tren canh ac lay diem n sao cho bm = cn . goi i la trung giem doan bn , goi k la trung diem doan cm , duong thang ik cat ab tai p , cat ac tai q . chung minh rang tam giac apq la tam giac can .
Cho tam giac abc vuong tai a ke ah vuong goc voi bc tai h. Hoi a,chung minh tam giac abh bang tam giac ach , ve trung tuyen bm goi g la giao diem cua ah va bm cm g la trong tam abc c, cho ab= 30 bh=18 tinh ah ag d, tu h ke hc song song ac cm 3 diem cgd thang hang
CHO ABC vuong tai A goi M la trung diem cua AC goij M la trung diem cua AC tren tia BM lay diem K sao cho MK bang MB
c/m tam giac BMC bang KMA
C/M tam giac ACK vuong
goi D la trung diem cua BC tia DM cat AK tai F c/m F la trung diem cua AK
Cho tam giac abc can tai A co 2 duong trung tuyen BM va CN
a)Chung Minh tu giac bcnm la hinh thang can
b)ke duong thang di qua m va song song voi CN cat BC tai D . CM tu giac NMDC la Hinh binh hanh
c) CM tam giac BMD la tam giac can va BD=3MN
d) goi AH la duong cao cua tam giac ABC va Q la diem doi xung voi H qua N. CM tu giac AHBQ la Hinh chu nhat
e) goi k la Hinh chieu cua H tren AC va I la Trung diem cua HK. Chung Minh AI vuong goc voi BK
cho tam giac ABC can tai A .Ten tia doi cua tia BC lay diem M ,tren tia doi cua CB lay diem N sao cho BM=CN.
a) cm tam giac AMN LA TAM GIAC CAN.
b) Cm AH=AK.
c) Goi O LA GIAO DIEM CUA HB va KC.tam giac OBC la tam giac gi,vi sao?
d) cm AO la tia phan giac cua MAN
Cho tam giac ABC. Tren canh BC lay M sao cho BM=2/3 BC. Tren tia doi cua tia CA lay A' sao cho CA'=CA. AM cat BA' tai N. Cm N la trung diem cua BA'
CHo tam giac ABC can tai A. Goi hai diem D va E lan luot la trung diem cua cac canh AB va Ac, hai doan thang Be va Cd cat nhau tai G
a, CM: AD= AE
b, Tren tia doi cua tia DC ta lay diem K sao cho DK= DG. CM: tam giac ADG= tam giac BDK, tu do suy ra AG song song BK
c, CM: BC + AG > 2*DE
a,Tam giác ABC cân tại A=> AB=AC
=> AD=BD=AE=EC
b,Xét tam giác ADG và tam giác BDK
GD=DK
ADG=BDK (đối đỉnh)
AD=DB (gt)
=> tam giác ADG=tam giác BDK
=>GAD=DBK
=> AG // BK(so le trong)
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cho tam giac abc vuong tai a goi M la trung diem cua AC tren tia BM lay diem k sao cho MK bang MB
c/m tam giac BMC bang KMA
c/m BC song song AK
goi D la trung diem cua BC tia DM cat AK tai F
c/m F la trung diem cua AK