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2018 AMC 10A Problem 21

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2018 AMC 10A Problem 21AMC 10 Step by Step
Name:                             Date: September 13, 2026
Coordinate Geometry · difficulty 4 of 5 · about 5 min · position P21-25

Which of the following describes the set of values of aa for which the curves x2+y2=a2x^2+y^2=a^2 and y=x2−ay=x^2-a in the real xyxy -plane intersect at exactly 33 points?

  1. A)

    a=14a=\frac14

  2. B)

    14<a<12\frac14 < a < \frac12

  3. C)

    a>14a>\frac14

  4. D)

    a=12a=\frac12

  5. E)

    a>12a>\frac12

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