Question

cho tam giac abc co ab=ac ,ah la phan giac cua goc a ,ve hdvuong goc ab he vuong ac

a , cm tam giac abh=tam giac ach

b) ah vuong goc bc

c ,de//bc

moi nguoi xem mk lm phan C dung ko nha .phan a,b mk bt lam roi

Answer 1

tu tam giac abh=tam giac ach

=>hb=hc(2 canh t/ư)

xet tam giac vuong adh va tam giac vuong aeh :

ah chung

a1=a2(gt)

=>tam giac v adh=tm giac v aeh

=>dh=eh(2 ......)

vi d nam giua a,b =>ad+db=ab

__ e nam giua a ,c=>ae+ec=ac

ma bd=ce,ab=ac

=>ad=ae

xet tam gisc adi va tg aei co

ai chung

a1=a2

ad=ae

=>tg adi=tg aei

=>i1=i2(2 goc t/ư)

ta co i1+i2=180(2 góc kề bù)

=>i1=i2=180:2=90o

=>ai vuong goc de hay ah vuong goc vs de

vi agvuong de

ah vuong bc

=>de //bc

Answer 2

moi nguoi xem mk lam dung ko vay

Answer 3

sai cho y kien nha