4AB=3AC và AB+AC=70
=>AB=30cm; AC=40cm
=>BC=50cm
4AB=3AC và AB+AC=70
=>AB=30cm; AC=40cm
=>BC=50cm
Cho tam giac ABC vuong tai A. Tinh canh BC biet: AB=AC va AB+AC=10 cm
Cho tam giac ABC vuong tai A. Tinh canh BC biet: AB+AC =17cm va AB-AC=7cm
cho Δ ABC vuong tai A co B =60 . tren canh BC lay diem D sao cho BA=BD . TIA phan giac cua B cat AC tai I
a, cm ΔBAD deu
b, cm ΔIBC can
c, CM D la trung diem cua BC
d, cho AB= 6cm . tinh BC va AC
cho tam giac abc vuong can tai a,ab =3 cm .qua a ke duong thang d ko cat canh bc.ke bh vuong goc voi d tai h,ck vuong goc voi d tai k
a) chung minh bh song song ck
b)tinh do dai canh bc va so do g minh
c)chung minh goc hab = goc ack
d)chung minh bh +ck =hk
cac ban thong cam ,t ko viet dc dau
Cho tam giac deu ABC. Tren canh AB lay diem D sao cho AD=1/3 AB. Tu D ke duong thang vuong goc AB cat A o E, qua E ke duong thang vuong goc AC cat BC o F. Chung minh. a, DF vuong goc BC. b, Tam giac DEF la tam giac deu
Cho tam giac ABC co goc A bang 90 do. Duong thang AH vuong goc voi BC tai H. Tren cung nua mat phang bo BC voi diem A sao cho AH=BD
a. Chung minh \(\Delta AHB=\Delta DBH\)
b. Hai duong thang AB va DH co song song khong? Tai sao?
c. Tinh goc ACB, biet goc BAH=35 do
cho tam giac ABC can tai A co A < 90 do, duong vuong goc voi AB tai B va duong thang vuong goc voi AC tai C va chung cat nhau tai M.
a, c/m tgABM = tgACM, AM la phan giac cua goc BAC
b, Qua M ve duong thang song song voi AC, duong thang nay cat AB o D. Tren tia doi cua tia CA lay diem E sao cho CE = DB, c/m tgDBM = tgECM
c, BC cat DM tai F. c/m DF = CE
cho ΔABC vuong tai A va ABC=60
a, so sanh AB va AC
b, Tren BC lay D sao cho BD =AB. Qua D dung cac duong thang vuong goc voi BC cat tia doi AB tai E. CHung minh ΔABC=ΔDEB
c, goi H la giao diem cua ED va AC. chung minh BH la tia phan giac cua ABC
d,Qua B dung cac duong thang vuong goc voi AB cat duong thang ED tai K vhng minh ΔHBK deu
cho tam giac ABC can tai a cs a =100.lay m thuoc canh ab, diem mn thuoc canh ac sao cho am=an .chung minh rang MN//Cm va Bn=Cm