Question

在△ABC中,AB=AC,AB的垂直平分线角交AB于D,交AC与E,若△ABC与△EBC周长分别为26cm.18cm.求

Answer 1

△ABC周长=2AB+BC=26cm,(1)

△EBC周长=BC+BE+CE=18cm,(2),

DE是AB的垂直平分线,

AE=BE,

BE+CE=AC,

AB=AC,

由2式得,BC+AC=18cm,(3),

(1)-(3)式,

AB=8cm,

∴AD=AB/2=4(cm).