Question

ABCD is a cyclic quadrilateral in which ABllDC if BAD = 105 find BCD and ABC

Answer 1

BCD =75
ABC =105
As in cyclic qud sum of opposite angle is 180

Answer 2

In a cyclic quadrilateral, opposite angles are supplementary. So,
Angle DAC+Angle DCB=180
=105+BCD=180
=BCD=180-105
=75.
AB||CD.
So,Angle BCD+Angle CBA=180(co-interior)
=75+CBA=180
Angle CBA=105