Triangle incicle, area and angles

This function calculates the area, angles and incircle of a triangle according to Heron's theorem. To calculate, enter the lengths of all three sides. Then click on Calculate. Please note that any two sides together must be longer than the third.

Calculate the triangle  Input Delete Entries Side a Side b Side c Decimal places 0 1 2 3 4 6 8 10  Results Area Height Angle α Angle β Angle γ Incircle area Incircle radius

Formulas for calculating the area of a triangle

Calculation from three given side lengths

The mathematician Heron's theorem describes a mathematical formula for calculating the area of a triangle from given three side lengths.

Alternative formulas

\(\displaystyle A = \frac{1}{4} · \sqrt{(a+b+c)·(-a+b+c)·(a-b+c)·(a+b-c)} \)

\(\displaystyle A = \frac{1}{4} · \sqrt{4·a^2·b^2-(a^2+b^2-c^2)} \)