Answer: 346/45
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Explanation:
Let point A be the center of the circle.
The inscribed angle CED doubles to the central angle CAD due to the inscribed angle theorem.
angle CAD = 2*(angle CED)
angle CAD = 2*(7x+6)
angle CAD = 14x+12
Angle CAD is the same as minor arc CD. These are two different ways to describe the same thing more or less. This is because the central angle subtends or cuts off the minor arc CD.
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The three arc pieces CE, ED and CD all combine to form a 360 degree circle.
(arc CE) + (arc ED) + (arc CD) = 360
(18x+1) + (13x+1) + (14x+12) = 360
(18x+13x+14x) + (1+1+12) = 360
45x+14 = 360
45x = 360-14
45x = 346
x = 346/45
This approximates to roughly x = 7.6889, but I have a feeling your teacher will want the fraction form.
