Triangle Calculator

Solve common triangle setups and get missing sides, angles, area, and perimeter from standard triangle inputs.

Preparing Triangle Calculator

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Input

Choose the triangle data you know first, then enter the side lengths or angle values needed for that case. You will see the result first and the step-by-step solution below.

Input summary

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Step by Step Calculation

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Calculate first and the full working will appear below automatically.

How to use Triangle Calculator

Select the triangle setup that matches your data, enter the known measurements, and the calculator will solve the remaining values that follow from that configuration.

What this calculator is for

This calculator is for triangle homework, design sketches, and geometry review when you need the unknown sides, interior angles, area, or perimeter from one of the standard triangle-information cases.

Tips

Make sure all sides use the same unit before solving.
For SAS, the entered angle must be the included angle between the two given sides.
If you use base and height only, treat the output as an area-first result unless extra side lengths are provided.