Cho tam giac abc vuong tai a .duong cao ah va d nam giua a va h tren tia doi cua ha lay diem e sao cho he =ad duong thang vuong goc voi ah tai d cat ac tai f . cm eb vuong goc voi ef
cho tam giac ABC vyong tai A duong cao AH va D nam giua A va H tren tia doi cua tia HA lay E sao cho HE = AD duong vuong goc voi AH tai D cat AC tai F chung minh rang EB vuong goc voi EF
Cho tam giác ABC (AB<AC:góc ABC khac 90 do)I la trung diem BC,Duong trung truc BCcat AC tại N.Tren tia BN lay BM=AC (N nam giua B va M)
a) CMR:AM song song BC
b)AB cat MC tai O. CMR ;3 diem O,N,I thang hang
Cho tam giac ABC co goc A lon hon 90 do. Ke DA vuong goc voi AB va DA=AB ( tia AD nam giua 2 tia AB,AC).Ke AE vuong goc voi AC va AE=AC ( tia AE nam giua 2 tia AB,AC). Ke AH vuong goc voi BC va keo dai cat De tai M. CM MD=ME
cho tam giac ABC can tai A tren canh BC lay hai diem D va E sao cho BD=DE=ECva diem D nam giua chung minh B va E ; a goc BAD = goc CAE ; b AD<AC ; c lay diem K thuoc tia doi cua tia EA sao cho EA=EK , chung minh CK=AD chung minh goc CAK <goc CAE ;e chung minh goc BAD < goc DAE
Cho <xOy Khác goc bet, Ot la TPG cua < xOy. Tren tia Ox lay A, tren tia Oy lay B ( A;B khac 0 ). Tia OF cat Ab tai C
a) CM: Tam giac AOC= tam giac BOc va tinh <ACO
b) Tren OC lay H nam giua O va C , dg thang AH cat OY tai D , dg thang BH cat OC tai E. CM HO la TPG cua <EHD
c)Dg thang CE cat AB tai M. dg thang CD cat BH tai N; MN cat Ot tai E. CM F la trung diem cua MN
cho tam giac abc vuong tai a co goc b>45 do,ve duong cao ah.tren tia ha lay diem p sao cho hp=hb,tren tia hc lay diem q sao cho hq=ha
a)cm p nam giua h va a,q nam giua h va c
b)cm qp song song vs ac
c)qua p ke duong thang song song vs bc cat ac tai d.tren tia ds cua tia ha lay diem e sao cho he=ap.tinh goc bed
Cho tam giac ABC vuong tai A co AB=4.5cm,AC=6cm, trung tuyen AM . Duong thang voi AC tai C cat tia AM tai N
a)Tinh do dai canh BC
b)Chung minh AN=2AM
c)Phan giac cua goc BAC cat BC tai D. Chung minh D nam giua B va M
(Nho ve hinh gium nha)
cho 3 diem A,B,C thang hang qua C ve mot duong thang lan luot cat cac duong trung truc cua AC va BC tai E va F Chung minh rang AE//BF