What is Heron's formula?

Heron's formula calculates the area of a triangle when you know all three side lengths: A = sqrt(s(s-a)(s-b)(s-c)), where s is the semi-perimeter.

Can I use this for right triangles?

Yes, this calculator works for all triangles including right, acute, and obtuse triangles.

Triangle Calculator

Enter the three sides of any triangle to find its area (Heron's formula), perimeter, and all three interior angles (law of cosines). Works for any valid triangle.

Inputs

Side a

Side b

Side c

Results

Area

6 sq units

Perimeter

Semi-Perimeter

Angle A

36.8699°

Angle B

53.1301°

Angle C

90°

Last updated: April 16, 2026

Frequently Asked Questions

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