Answer:
arc AD = 126°
Step-by-step explanation:
the inscribed angles ABD and ACD are half the measure of their intercepted arc AD
then ∠ ABD and ∠ ACD are congruent , so
11x - 3 = 8x + 15 ( subtract 8x from both sides )
3x - 3 = 15 ( add 3 to both sides )
3x = 18 ( divide both sides by 3 )
x = 6
then
∠ ABD = 11x - 3 = 11(6) - 3 = 66 - 3 = 63° , thus
arc AD = 2 × 63° = 126°
