Angle CED must also measure 60°. Because angle m is shown to be congruent to angles ABC and CDE, this means that angle m has a measure of 60 degrees. There can only be 180 degrees in a triangle, so the measure of angle ACB must be 180-60-60, which equals 60 degrees. Using the Vertical Angles Theorem, the measure of angle ACB is the same as the measure of angle CED. Therefore, angle CED measures 60°.