I think this solution is wrong. If one angle is 90, then the opposite is 90 and the two remaining angles are equal, because it is a cyclic quadrilateral. Because it is a quadrelateral, all angles sum 360. Hence, the two remaining angles must also be 9. (So A is also correct).
How does this line of reasoning follow?
All angles must sum 360 because it is a quadrilateral. We already have two opposing 90 angles. Hence, the sum of the two remaining opposite angles must be 180. Because it is a cyclic quadrilateral, these angles must be the same. Hence, they should be 90 too.
I get you up to here. But that does not tell anything about the other two angles - there is no evidence we are dealing with a parallelogram.
Right, sorry. I am just having trouble imagining a quadrilateral where two opposite angles are 90 degrees and the two remaining ones are not 90.
the two remaining ones just have to sum up to 180.
Sorry. Feel free to delete thread if may cause confusion