If ABCD is a cyclic quadrilateral, then which of the angles given add up to 180∘?
∠ABC and ∠BCD
∠BAD and ∠ADC
Opposite angles are supplementary in a cyclic quadrilateral. i.e., They add up to 180∘. Thus, ∠ADC+∠ABC=180∘ and ∠BAD+∠BCD=180∘.
ABCD is a cyclic quadrilateral. Then which of the given angles add to 180∘?