Taking the two right sides AB and BC of the right triangle ABC as one side, make the equilateral triangle △ Abe and equilateral △ BCF outward respectively, connecting EF and EC. Try to explain: (1) EF = EC; (2) EB ⊥ CF

Taking the two right sides AB and BC of the right triangle ABC as one side, make the equilateral triangle △ Abe and equilateral △ BCF outward respectively, connecting EF and EC. Try to explain: (1) EF = EC; (2) EB ⊥ CF

It is proved that ∵ Abe and ∵ BCF are equilateral triangles, ∵ AB = be, BC = BF, ∵ Abe = ∵ CBF = 60 °, ∵ ABC = 90 °, ∵ CBE = 90 ° + 60 ° = 150 °, ∵ EBF = 360 ° - 60 ° × 2-90 ° = 150 °, ∵ EBF = ∵ CBE. In ∵ BCE and ∵ BFE, ab = be ∵ EBF = ∵ cbebc = BF