數學問題(冇人識答定唔肯答?.?) [複製鏈接]

In this figure,triangleABC and triangleECD are equilateral triangles.BCD,BGEF and AFHD are straight lines
Show that CG=CH
新鮮出爐考試題目=v=

搵cg同ch啲咩._.?
重有尒比啲資料吾夠-.-

angle ACH = 180 - 60 - 60 =60 degrees

BC=AC
CE=CD
angle BCE = angle ACD = 120 degrees

triangle BCE and ACD are congruent (S.A.S)

AC=BC
angle ACH = angle BCG = 60 degrees
angle HAC = angle GBC (corr . angles, congruent triangles)

so, triangle ACH and BCG are congruent (A.S.A)
so, CG=CH (corr. sides, congruent triangles) 

angle ACH = 180 - 60 - 60 =60 degrees

BC=AC
CE=CD
angle BCE = angle ACD = 120 degrees

triangle BCE and ACD are congruent (S.A.S)

AC=BC
angle ACH = angle BCG = 60 degrees
angle HAC = angle GBC (corr . angles, congruent triangles)

so, triangle ACH and BCG are congruent (A.S.A)
so, CG=CH (corr. sides, congruent triangles)