16Hit1600
Advanced MathVery hardNumber of intersection points of a line and a circle

Advanced Math practice question

In the xy-plane, how many points do the graphs of x² + y² = 25 and y = 7 have in common?

  1. A. NoneCorrect
  2. B. Exactly one
  3. C. Exactly two
  4. D. Infinitely many

Answer: A. None

The circle has radius 5, so no point on it has y = 7 (substituting gives x² = 25 − 49 < 0).

Why the other answers are wrong

B. Exactly one
Exactly one would need the line tangent, at y = 5 or y = −5.
C. Exactly two
Two would need |y| < 5.
D. Infinitely many
A line and a circle never share infinitely many points.

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