Engineering Board Exam Reviewer · Circles · hard

A circle passes through (1,2) and (5,4) and its center lies on the x-axis. Find its radius.

  1. 4.5
  2. 4.03
  3. 3.5
  4. 5

Answer

B. 4.03

Solution

Let the center be (h,0). Equal distances: (h-1)2+4=(h-5)2+16 8h=36 h=4.5. r=sqrt((3.5)2+4)=sqrt(16.25)=4.03.

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