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Fengxian 20 15 Senior Three Mathematics Module 2
Prove: (1)∵ equilateral △ABC and equilateral △ADE,

∴AB=AC,AE=AD,∠CAB=∠EAD=60,

∠∠BAE+∠EAC = 60,∠DAC+∠EAC=60,

∴∠BAE=∠CAD,

In △AEB and △ADC,

AB=AC∠BAE=∠CADAE=AD

∴△aeb≌△adc(sas);

(2) Solution: The shape of quadrilateral BCGE is a diamond,

The reason is: ∫△AEB?△ADC.

∴∠ABE=∠ACD,BE=CD,

∠∠ABC =∠ACB = 60,

∴∠ABE=∠ACD=∠BCG= 120,

∴∠DBE=60,

∴∠BCG+∠DBE= 180,

∴BE∥CG,

∵BC∨EG,

∴ quadrilateral BCGE is a parallelogram,

BC = CD,

∴BE=BC,

∴ Quadrilateral parallelogram BCGE is a diamond.