What is the measure of ac ? enter your answer in the box.

To solve for AC in the given inscribed angle we proceed as follows:
An inscribed angle is an angle with its vertex "on" the circle formed by two intersecting chords as in our drawing. Thus here we shall use the formula:
Inscribed Angle=1/2 intercepted Arc
thus
m∠ABC=1/2mAC
thus plugging in our values we shall have:
4x-3.5=1/2(4x+17)
4x-3.5=2x+8.5
solving simplifying and solving for x we obtain
4x-2x=8.5+3.5
2x=12
hence
x=12/2
x=6°

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