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 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 goc xOy khac goc bet ,ot la tia phan giac cua goc do .tren tia ot lay diem H,qua H ve duong thang vuong goc voi tia ot,cat Ox tai A va Oy tai B

chung minh tam gic AHO bang tam giac BHO

tren tia Ax lay diem C tren tia By lay diem D sao cho AC=BD.chung minh AD=BC

cho CD cat tia ot tai diem K .chung minh AB song song voi CD

cho \(\widehat{xAy}\)= 60 do ve tia phan giac AZ cua goc do tu 1 diem B tren tia AX ve duong thang song song voi voi Ay cat Az tai C.ke BH vuong goc voi Ay CM vuong goc voi Ay tai M BK vuong goc voi AC tai K

a)KC=KA

b)\(BH=\frac{AC}{2}\)

c)tam giac KMC deu

Cho goc xAy=60 do.Ve tia phan giac Az cuc goc do.Tu mot diem B tren Ax ve duong thang song song voi Ay cat Az tai C.Ve BH vuong goc Ay;Bk vuong goc AC,Chung minh rang:

a,K la trung diem cua AC.

b,BH=AC/2

c,KMC deu

cho tam giac ABC can o A.Tren canh BC lay diem D, tren tia doi cua tia CB lay diem E sao cho BD=CE.Tu D ke duong thang vuong goc voi BC cat AB o M, tu E ke duong thang vuong goc voi BC cat AC o N.Chung minh:

a)MD=ME

b)MN cat DE o I. Chung minh I la trung diem cua DE

c)Tu C ke duong thang vuong goc voi AC, tu D ke duong thang vuong goc voi AB.Chung cat nhau tai O.Chung minh AO la duong trung truc cua BC

cho goc nhon xOy. lay diem A thuoc tia Ox, lay diem B thuoc tia Oy sao cho OA=OB. Qua A ke duong thang vuong goc voi Ox cat oy tai M, qua B ke duong thang vuong goc voi Oy cat Ox tai N. goi H la giao diem cua AM va BN, I la trung diem cua MN. chung minh rang:

a) ON =OM va AN=BM

b) tia OH la tia phan giac cua goc xOy

c) ba diem O,H,I thang hang

cho doan thang AB co O la trung diem .Ve Ax va By vuong goc voi AB tai Ava B .Lay C tren Ax , duong thang vuong goc voi OC cat By tai D.CMR DC=AC+BD.??????????????????????

        BAN NAO GIUP MINH NHANH NHAT MINH TICH CHO<3

cho duong tron (O;R) va duong thang d co dinh khong cat duong tron.tu mot diem A bai ki tren duong thang d ke tiep tuyen AB voi duong tron (B la tiep diem ).tu B ke duong thang vuong goc voi Ao tai H tren tia doi cua tia BH lay C sao cho HC=HB.

a,chung minh C thuoc duong tron (O;R) va AC la tiep tuyen cua (O;R).

b,tu Oke duong thang vuong goc voi duong thang d tai i,OI cat BC tai K.chung minh OH.OA=OI.OK=R^2

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