Answer:
m<AOB = 50°
Step-by-step explanation:
<ACB = 25° is an inscribed angle of the circle.
<AOB is a central angle of the circle.
Thus, based on the inscribed angle theorem which states that an inscribed angle is ½ the measure of the central angle, therefore:
m<ACB = ½(m<AOB)
Substitute
25° = ½(m<AOB)
Multiply both sides by 2
2*25 = m<AOB
m<AOB = 50°
