Answer:
C. ±square root of 30
Step-by-step explanation:
Apply the square root function to both sides of the equation:

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The absolute value equation has two solutions. They match choice C.
Paraphrase the following steps:
•Draw a line connecting the point to the center of the circle
•Construct the perpendicular bisector of that line
•Place the compass on the midpoint, adjust its length to reach the end point, and draw an arc across the circle
•Where the arc crosses the circle will be the tangent points.
X=15, all you have to do is multiply