1 cho tam giac abc can a , goc a bang 40 do lay d khac phia b so voi ac thoa man goc cad bang 60 do goc cad bang 80 do chung minh bd vuong goc voi ac

2 cho tam giac abc vuong can a . d la diem bat ki tren ab. tren nua mat phang bo ab tu c ve tia bx sao cho goc abx bang 135 do. duong thang  vuong goc voi dc ve tu d cat bx o e . chung minh tam giac dec vuong can

3 cho tam giac abc can b goc abc bang 80 do , i la diem trong tam giac sao cho goc iac bang 10 do, ica bang 30 do tinh goc abi

4 cho tam giac abc can a co goc a bang 100 do , bc =a, ac =b ve phia ngoai tam giac abc ve tam giac abd can d co goc adb bang 140 do tinh ch vi tam giac adb theo a,b

ve hinh gium minh voi , xin mn day

Cac ban hay giai cac bai toan sau day:

1. Biet d dai ba canh cua 1 tam giac lan luot ti le voi 3,4,5 va co chu vi bang 96 cm . Tinh do dai 3 canh cua tam giac do. 

2. Cho tam giac ABC vuong tai A . Goi M la trunng diem cua AC . Tren tia doi cua tia MB lay diem D sao cho MB = MD

A. Biet ABC =55° . Tinh goc ACB 

B . Chung minh tam giac ABM = tam giac CDM

C. Chung minh ABC = CDA

3. Me dua An 2.800.000 de dong tien dien , nuoc , internet lan luot theo ti le 7;5;2 . Ban hay giup An tinh tien dien , nuoc , internet ?.

4. Cho tam giac ABC vuong tai A ( AB < AC ) , goi M la trung dim cua AC . Tren tia doi cua MB lay diem D sao cho MB = MD 

A. Chung minh tam giac ABM = tam gac CMD

B. Chung minh DC song song AB 

C. Tinh goc CDM 

D. Chung minh DC vuong goc voi AC.