The line is a tangent to the circle . Find the possible values of .

Answer and explanation

Correct answer: A. or

  1. Step 1: Substitute: , giving .
  2. Step 2: Tangent means equal roots: .
  3. Step 3: , so and .
Answer
or .
Why not the others: : the radius was used as the intercept. or : the discriminant was set up wrongly. or : the radius squared was used as .

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