ms hok lóp 7 thông cảm nhá sory zery much
ms hok lóp 7 thông cảm nhá sory zery much
cho tam giac ABC nhon co 3 duong cao AD , BE , CF cat nhau tai H CMR a)DB*DC=DH*DA.b)tam giac ABC dong dang voi tam giac AEF.c)DH/AD +HE/BE+HF/CF=1.d) H la giao diem cac duong phan giac cua tam giac DEF
cho tam giac abc vuong tai a,co ab=9,bc=15
a) tinh do dai canh ac va so ssanh cac goc cua tam giac abc
b) tren tia doi cua tia ab lay diem d sao cho a la trung diem cua doan thang bd.chung minh tam giac bcd can
c) goi k la trung diem cua canh bc. duong thang dk cat canh ac tai m.tinh do dai doan thang mc
d) duong trung truc cua canh ac cat duong thang dc tai q.chung minh ba diemb,m.q thẳng hàng
cho hinh binh hanh ABCD tren cac canh AB,CD dan dan lay cac diem MN sao cho AM=DN duong trung truc cua BM lan luot cat cac doan thang MN va BC tai E va F CMR:
a) EF doi xung voi nhau qua AB
b)tu giac MEBF la hinh thoi
BAI 1
Cho tam giac ABC co BC = 8cm,cac trung tuyen BD , CE .Goi M , N theo thu tu la trung diem cua BE va CD .Goi giao diem cua MN voi BD,CE theo thu tu la I,K
a,Tinh do dai MN
b, CMR;MI = IK = KN
BAI 2
Cho hinh thang ABCD(AB//CD). Cac duong fan giac cua cac goc ngoai tai dinh A va D cat nhau tai M.Cac duong fan giac cua cac goc ngoai tai dinh B va C cat nhau tai N
a,CMR ;MN//CD
b,Tinh chu vi hinh thang ABCD biet MN =4cm
NHO CAC BAN GIUP VOI NHA
Cho tam giac ABC nhon, ba duong cao AD,BE,CF cat nhau ta H.Qua A ve cac duong thang song song voi BE,CF lan luot cat cac duong thang CF,BE tai P,Q. Cmr
a, AE.AC=AF.AB
b, PQ vuong goc voi trung tuyen AM cua tam giac ABC
Cho tam giac abc duong cao bd,ce. h la giao cua db va ce. m,n thuoc bd,ce sao cho bm=hn. cmr trung truc mn luon di qua 1 diem co dinh
Cho tam giac ABC nhon , cac duong cao AD, BE,CF cat nhau tai H, ve DM vuong goc AC tai M. Goi K la giao diem CH va DM
C/m : CD/BD=CM/EM va BH/EH=DK/MK
cho tam giac ABC tren cac canh BC,CA,AB lay cac diem D,E,F sao cho AD,BE,CF cat nhau tai H. CMR: AH/AD+BH/BE+CH/CF=2
Giai ho minh bai nay minh cn ngay
Bai 1 cho tam giac ABC cac trung tuyen BM ,CM cat nhau tai G Goi P la diem doi xung voi M qua G goi Q la diem doi xung voi N qua G CM
a tu giac MNPQ la hinh gi vi sao
b neu tam giac ABC can tai A thi tu giac MNPQ la hinh gi vi sao
Bai 2 cho tam giac ABC M la diem bat ky tren BC Qua M ke duong thang song song voi AC cat AB tai D Qua M ke duong thang song song voi AB cat AC tai E goi I la trung diem cua AM Cm
a 3 diem D,E,Ithang hang
b khi M di chuyển trên BC thì I di chuyển trên đường nào
Bai 3 cho tam giac nhon ABC truc tam H va giao đường trung truc la diem O goi P,Q,N theo thu tu trung diem cua Ab,AH,AC CM
a tu giac OPQN la hinh binh hanh
btam giac ABC can co them dieu kien gi de tu giac OPQN la hinh chu nhat
