Circumcenter Calculator

Find the circumcenter, circumradius, and related properties of a triangle from its vertex coordinates.

Point A

Point B

Point C

Results

Circumcenter X

3.00

Circumcenter Y

0.88

Circumradius

3.13

Side Lengths

Circumcenter Calculator

PropertyValue
Circumcenter X3.0000
Circumcenter Y0.8750
Circumradius3.1250
Triangle Area12.0000
Perimeter16.0000
Side a (BC)5.0000
Side b (AC)5.0000
Side c (AB)6.0000

About the Circumcenter

What Is the Circumcenter?

The circumcenter of a triangle is the point where the perpendicular bisectors of all three sides intersect. It is equidistant from all three vertices, making it the center of the circumscribed circle (circumcircle). The circumcircle passes through all three vertices of the triangle.

Finding the Circumcenter

Given three vertex coordinates A(x1,y1), B(x2,y2), and C(x3,y3), the circumcenter (ux, uy) is found using the formula that solves the system of equations arising from the equal distance condition. The circumradius R equals the distance from the circumcenter to any vertex.

Properties

The circumcenter has important properties: it is equidistant from all three vertices, the circumradius R = (abc)/(4A) where a,b,c are side lengths and A is the area. For an acute triangle, the circumcenter lies inside; for an obtuse triangle, it lies outside; for a right triangle, it lies at the midpoint of the hypotenuse.

Applications

Circumcenter calculations are used in computational geometry, Delaunay triangulation, mesh generation, GPS trilateration, and computer graphics. The circumcircle is the smallest circle that passes through all three vertices.

Practical Example

Triangle A(0,0), B(6,0), C(3,4)

Step 1: Side a (BC) = sqrt((6-3)² + (0-4)²) = 5

Step 2: Side b (AC) = sqrt((3-0)² + (4-0)²) = 5

Step 3: Side c (AB) = sqrt(36) = 6

Step 4: Circumcenter = (3, 1.75)

Step 5: Circumradius R = 3.125

Preguntas Frecuentes

What is the circumcircle?

The circumcircle is the unique circle that passes through all three vertices of a triangle. Its center is the circumcenter and its radius is the circumradius.

Where is the circumcenter for a right triangle?

For a right triangle, the circumcenter is at the midpoint of the hypotenuse. The circumradius equals half the hypotenuse length.

Can the circumcenter be outside the triangle?

Yes. For obtuse triangles, the circumcenter lies outside the triangle. For acute triangles it is inside, and for right triangles it is on the hypotenuse.

What is the relationship between circumradius and area?

R = (abc)/(4A), where a, b, c are side lengths and A is the triangle area. This is known as the extended law of sines.

Is the circumcenter the same as the centroid?

No. The circumcenter is the intersection of perpendicular bisectors, while the centroid is the intersection of medians. They coincide only in equilateral triangles.

Disclaimer: This calculator uses standard geometric formulas. Results are for informational purposes only.

References

  1. Wikipedia. "Circumcircle." en.wikipedia.org
  2. Wolfram MathWorld. mathworld.wolfram.com

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