Internal Angle Bisector Calculator

units
Enter side a in units.
units
Enter side b in units.
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Enter side c in units.
Math

Internal Angle Bisector: calculate results from explicit inputs, with a formula and worked example.

Formula

lₐ = √[bc((b+c)²−a²)]/(b+c)

Example Calculation

Example inputs
  • Side a: 3 units
  • Side b: 4 units
  • Side c: 5 units

For sides 3, 4 and 5, the bisector from A is approximately 4.2164 units.

Frequently asked questions

How do I use this calculator?

Enter side a, side b, side c. The result updates automatically. Use Reset to restore the example values.

What method does it use?

lₐ = √[bc((b+c)²−a²)]/(b+c). Euclidean geometry. Use one consistent length unit; areas and volumes use its square and cube. Degenerate shapes are rejected. Very thin shapes may lose floating-point precision.

Why might a rounded result differ?

The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.

Are my inputs saved online?

No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.

Check the assumptions and units before using this result. Read about calculation methods.