Question

In the diagram below, if < ACD = 54 °, find the measure of < ABD

Answer 1

Opposite angles in a quadrilateral inscribed in a circle add up to 180, therefore:

`\begin{gathered} m\angle ACD+m\angle ABD=180 \\ 54+m\angle ABD=180 \\ m\angle ABD=180-54 \\ m\angle ABD=126^(\circ) \end{gathered}`

Answer:

b. 126