Answer:
Arc GH = 78°
Explanation:
Inscribed angle = m<GIH = 39°
Measure of arc related to inscribed angle = arc GH = ?
Thus:
m<GIH = ½(arc GH) => Inscribed angles theorem
Substitute
39° = ½(arc GH)
Multiply both sides by 2
2*39° = arc GH
78° = arc GH
Arc GH = 78°