We want to find the measure of arc AD. We would need to find x first as this would guide us toward finding AD.
We know from a circle geometry theorem that;
I. Angles in the same segment are equal. In this case,
Therefore, we can equate them, equating them we obtain;
We could use this to obtain the measures of angle ABD or ACD, obtaining one is enough as they are congruent, let us use
We can therefore find the measure of angle AD, by using the circle geometry theorem;
ii. Angles subtended at the centre of a circle is twice that subtended at the circumference;
Thus;
Therefore, the measure of arc AD is 126 degrees.