As shown in the figure, AB is the diameter of the circle O, ad = De, AE and BD intersect with point C, then there are several angles equal to angle BCE in the figure
There are two angles which are equal to the angle BCE in the figure, they are: ∠ ACD (opposite to the vertex angle) and ∠ bad ∠ bad = ∠ BCE, the reason is as follows: ad = De, we can get: ∠ DAE = ∠ AED and ∠ abd = ∠ AED (equal to the circumference angle of the same arc), then ∠ DAE = ∠ abd, because in RT △ abd, ∠ DAB + ∠ abd = 90 ° in RT △ ADC