∫△ABC and△△△ CDE are equilateral triangles;
∴∠acb=∠dce=600;
∴∠ace=∠bcd = 180-60 = 1200;
∫△ABC and△△△ CDE are equilateral triangles;
∴bc=ac; DC = EC;
∴△BCD is the same as△△△ ACE.
* * * The same point is C, ∠ ACB = 600; So the center of rotation is point C, and the rotation angle is 60 degrees.