Part 1
Answer: one half
The angle ABC is one half of minor arc AC
Explanation: A minor arc is any arc that has measure less than 180 degrees (ie smaller than half the circle). Due to the inscribed angle theorem, any inscribed angle is always one half of the arc it cuts off
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Part 2
Answer: 80 degrees
Explanation: Angle ABC is 40 degrees as shown in the diagram. Minor arc AC is 80 degrees since the inscribed angle is half of the arc. Put another way, the arc is twice that of the inscribed angle. This is something you should put in your notebook or on a reference card
- inscribed angle = (1/2)*arc
- arc = 2*(inscribed angle)
So we can say
minor arc AC = 2*(inscribed angle)
minor arc AC = 2*40
minor arc AC = 80 degrees
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Part 3
Answer: 280 degrees.
Explanation: Major arc ABC and minor arc AC combine to get the full circle of 360 degrees. We know minor arc AC is 80 degrees, so 360-80 = 280 is the remaining bit.