16Hit1600
Geometry and TrigonometryHardWhich point is inside a given circle

Geometry and Trigonometry practice question

A circle in the xy-plane has centre (1, −2) and radius 5. Which of the following points lies INSIDE the circle?

  1. A. (4, 1)Correct
  2. B. (6, −2)
  3. C. (1, 4)
  4. D. (−3, −5)

Answer: A. (4, 1)

(4, 1) is √(9 + 9) = √18 ≈ 4.2 from the centre, less than 5: inside.

Why the other answers are wrong

B. (6, −2)
(6, −2) is exactly 5 from the centre — ON the circle.
C. (1, 4)
(1, 4) is 6 from the centre — outside.
D. (−3, −5)
(−3, −5) is √(16 + 9) = 5 — on the circle.

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