A: ASB = ABS = bad = Abd = X.

b:ASB=x，ADB= 180-2x

C:AD∨BC, BCD+x= 180, BAD+BCD= 180, BAD=x=ABS, AS∨CD is an isosceles trapezoid, AB=CD, AC=BD, then Abd = ADC = X.

D: According to C, three internal angles of two triangles are equal, so two triangles are similar triangles.

(2)

A: A is the center of the circle, AB=AD, ABD=ADB=x, BAD= 180-2x.

B: ABCD is a diamond, BCD=BAD= 180-2x.

C: a is the center of the circle, and B is on the circle. Extend the intersection of BA to N and connect DN, then BED=BND.

BN is the diameter, BDN = 90 °, BND = 90-x = BED, BCD =180-bed = 90+x.

d:90+x= 180-2x，x=30