Current location - Training Enrollment Network - Mathematics courses - The second year of emergency mathematics-the eighth day of the second year "quick test before and after class".
The second year of emergency mathematics-the eighth day of the second year "quick test before and after class".
Proof: because AD=BE=CF

So BD=CE=AF

Because A=B=C=60 degrees.

So the triangle ADF, bed and CFE are congruent, so DE=EF=FD.

So the triangle DEF is an equilateral triangle.

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