Question

Answer 1

a, Xet tam giac ABC vuong tai A, duong cao AH

* Ap dung he thuc : \(AH^2=BH.CH\Rightarrow AH=\sqrt{16}=4cm\)

b, Do AB = AC => tam giac ABC can tai A

=> AH la duong cao dong thoi la duong phan giac 

Xet tam giac AMH va tam giac ANH co 

^AMH = ^ANH = 90⁰

^MAH = ^NAH ( AH la duong phan giac ) 

AH _ chung 

Vay tam giac AMH = tam giac ANH ( ch - gn )

=> AM = AN (1) ; Lai co : BA - AM = MB ; AC - AN = NC

=> MB = NC (2) 

Lay (1) . (2) ta duoc AM . MB = AN . CN