Violympic toán 8
Các câu hỏi tương tự
Cho hinh thang can ABCD co day nho CD=4cm; A+B=1/2(C+D), AC vuong goc BC. Chu vi hinh thang can abcd
cho hinh vuong ABCD. Qua A ve hai duong thang vuong goc voi nhau lan luot cat BC tai P va R, cat Cd tai Q va S.
a, chung minh tam giac AQR va tam giac APS la cac tam giac can
b, QR cat PS tai H; M,N la trung diem cua QR va PS. chung minh tu giac AMHN la hinh chu nhat
c, chung minh P la truc tam
d, chung minh MN la duong trung truc cua AC
e, chung minh bon diem M, B,N,D thang han
cho hinh vuong abcd co ac cat bd tai o.m la diem bat ki thuoc canh ad(m khac d,a).tia bm cat duong thang cd tai n,om cat an tai i.C/m di vuong goc voi an
Cho Hinh thang ABCD co : AB = 4cm , CD = 9cm ,goc ADB = goc BCD
a) CR : tam giac ABE dong dang tam giac ADC
b) Tinh BD
cho hinh vuong abcd, ac cat bd tai e, duong thnag qua a cat bc tai m , cat duong thang cd tai n,em cat bn tai k. chung minh ck vuong goc voi bn
cho tam giac ABC vuong tai A co AB=9cm BC=15cm tren tia doi cua tia AB lay diem D sao cho A la trung diem cua doan thang AB
a, tinh do dai canh AC va ss cac goc cua tam giac ABC
b, cm tam giac BCD can
c, goi E la trung diem cua canh CD ,BE cat AC o I .cm DI ik qua trung diem cua canh BC
(ve hinh )
bai 8 ; cho hinh chu nhat abcd . ke an,cm cung vuong goc voi bd .
a ) chung minh dn = bm .
b ) chung minh tu giac ancm la hinh binh hanh.
c) goi k la diem doi xung voi a qua n . tu giac dkcb la hinh gi . chung minh .
d ) tia am cat tia kc tai p . chung minh cac duong thang pn,ac,km dong quy .
cho hbh ABCD ,ve AH vuong goc CD,CK vuong goc AB chung ming tu giac AHCK la hinh gi vi sao ,chung minh AC,BD dong quy
cho tam giac abc vuong can (ab=ac). Qua C ve duong thang cat canh AB tai D. Tu B ve duong vuong goc voi CD tai I cat AC tai E. CMR AD=AE