Answer:
Arc BC = 117°
Explanation:
Angle D is an inscribed angle that intercepts arc ABC. According to the Inscribed angle theorem of a circle, m<D = ½ of arc ABC.
Thus,
104° = ½(AB + BC)
104° = ½(91° + BC)
Multiply both sides by 2
104*2 = 91 + BC
208 = 91 + BC
Subtract both sides by 91
208 - 91 = BC
117 = BC
Arc BC = 117°