如图,在△ABC中,AB =AC,点D、E、F分别在AB、BC、AC边上,且BE= CF,BD= CE. (1)求证:△DEF是等腰三

2025-02-24 10:51:51
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回答1:

解:(1) ∵AB=AC,∴ B= C.     
 在△BDE与△CEF中
BDE≌ CEF.
∴DE =EF.
即△DEF是等腰三角形.
(2)由(1)知△BDE≌△CEF,
BDE= CEF.
CEF+ DEF= BDE+ B,
DEF= B,
∴AB= AC, A= 40
DEF= B=