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The standard form of a circle equation is (x − h)² + (y − k)² = r², where (h, k) is the centre and r is the radius. This form makes it easy to identify the centre and radius directly.

공식

(x − h)² + (y − k)² = r²
h
x-coordinate of center
k
y-coordinate of center
r
radius (length)
x
x-coordinate on circle
y
y-coordinate on circle

단계별 가이드

  1. 1Standard form: (x − h)² + (y − k)² = r²
  2. 2Centre is at (h, k)
  3. 3Radius r = √[(x−h)² + (y−k)²]
  4. 4Area = πr², Circumference = 2πr

풀어진 예시

입력
Centre (2, 3), r = 5
결과
(x − 2)² + (y − 3)² = 25
입력
Centre (0, 0), r = 7
결과
x² + y² = 49

자주 묻는 질문

What is the general form of a circle equation?

The general form is x² + y² + Dx + Ey + F = 0. You can convert to standard form by completing the square.

Can a circle have a center not at the origin?

Yes! Any point (h, k) can be the center. The standard form directly shows the center and radius.

How do I find the center and radius from the general form?

Complete the square: h = −D/2, k = −E/2, and r² = h² + k² − F.

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