Circumscribed Circle Calculator

Find the circumradius of a triangle from its three sides.

Circumradius 2.5

Triangle area 6

Formula: R = abc ÷ (4 × area)

Step-by-step with your numbers:

1. Values used:

2. Side a = 3

3. Side b = 4

4. Side c = 5

6. Circumradius = 2.5

7. Triangle area = 6

Did we solve your problem today?

The circumscribed circle passes through all three vertices of a triangle.

The math behind it

The circumradius is R = abc ÷ (4·Area), where the area comes from Heron's formula.

Sides 3, 4, 5 → area 6, circumradius 2.5 (half the hypotenuse for a right triangle).

Where is the centre?

At the circumcentre, where the perpendicular bisectors of the sides meet.