Math calculator

Isosceles Triangle Area Calculator

Equal side lengthBase length

Triangle area: -

Visual representation

Isosceles Triangle Area Calculator diagram

The diagram updates with your entries and is illustrative, not necessarily drawn to scale.

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Calculation explained

How this result was calculated

The formula, your substituted values, and the evaluated result are shown below.

Two equal sides are assumed. The base must be positive and shorter than twice the equal-side length.

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How the Isosceles Triangle Area Calculator works

Calculate isosceles triangle area from its equal side and base lengths.

Formula

base × √(equalSide × equalSide-base × base ÷ 4) ÷ 2

How to use this calculator

Enter every measurement using one consistent length or angle unit.
Select Calculate to evaluate the formula.
Review the substituted values in the calculation explanation.

Interpretation and limitations

Two equal sides are assumed. The base must be positive and shorter than twice the equal-side length. Decimal answers are rounded for display; retain additional precision for subsequent calculations.

Geometry collection

This calculator belongs to the Plane Geometry section of the Math calculator library.

About this calculator