cho tam giac ABC, cac duong phan giac AD,BE cat nhau tai O.Cho biet DE la tia phan giac cua goc ADC.Tinh so do goc BOC. Cac ban lam on giup minh nha
lam on giup nha cho tam giac abc , cac duong han giac ad va be cat nhau tai o, biet de la phan giac goc adc. tinh goc boc
Cho tam giac ABC.Cac duong phan giac AD va BE cat nhau tai O. Biet DE la tia phan giac cua goc ADC. Tinh so do goc BOC.
CHo tam giac ABC can tai A co goc A la goc nhon. Ve hai duong cao AD va BE cat nhau tai H ( D thuoc BC, E thuoc AC)
a, Cm: Tam giac ABD= tam giac ACD
b, Duong thang CD cat AB tai F. CM; CF la duong cao cua tam giac ABC
c; CM; EF song song BC
Cho tam giac ABC. Hai duong phan giac ngoai ( duong phan giac ngoai la duong phan giac cua goc ngoai tam giac) cat nhau tai I. CMR AI la tia phan giac goc A
1.cho tam giac ABC co goc B-C=alpha phan giac AD
a) tinh gocADC,ADB theo alpha
b)Ve duong cao AH tinh goc HAD
2.chotam giac ABC,gocA =alpha,cac tia ohan giac cua B va C cat nhay tai I.Phan giac cat goc ngoai tai dinh B,C cat nhau tai K.Tia p/g goc B cat goc ngoai o dinh C.tinh cac goc BIC,BKC,BEC theo alpha.
giai bai tap; cho tam giac abc la tam giac nhon. tia phan giac cua goc bac cat bc tai d. tren canh ac lay diem e sao cho ae=ab. chung minh: a. db=de b.ad la duong trung truc cua be c. goc c bang 40 do, goc edc bang 30 do. tinh goc a va goc b cua tam giac abc
cho tam giac abc la tam giac nhon. tia phan giac cua goc bac cat bc tai d. tren canh ac lay diem e sao cho ae=ab. chung minh: a. db=de b.ad la duong trung truc cua be c. goc c bang 40 do, goc edc bang 30 do. tinh goc a va goc b cua tam giac abc
cho tam giac abc co goc a= 75 do gooc b=35 do. phan giac cua goc a cat bc taii d. duong thang qua a vuong goc voi ad cat duong thang bc tai e. goi m la trung diem cua de. cmr
tam giac acm can