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Triangle Calculator

Solve a triangle from its three sides, including angles, area, perimeter and heights.

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1. Set up your calculation

Sides must be positive, use one consistent unit and satisfy the triangle inequality. Angles are opposite the correspondingly named sides. Near-degenerate triangles may lose numerical precision.

2. Review & use your result

Review the example inputs, then use solve triangle.

Report / export preview

Generated file contents

Using Triangle Calculator

Solve a triangle from its three sides, including angles, area, perimeter and heights.

Enter side a and side b. Try the example to see the format.
Solve triangle and review the result, including the assumptions shown below the inputs.
Copy, download or print your result. Editing an input clears the previous result.

Example

The included example: Area (square units) — 6; Perimeter — 12.
Change the inputs and generate a new result to compare it.

Questions & answers

How do I use this tool?

Solve a triangle from its three sides, including angles, area, perimeter and heights. Load the editable example, replace its values and use the main action button.

What should I check before using the result?

Sides must be positive, use one consistent unit and satisfy the triangle inequality. Angles are opposite the correspondingly named sides. Near-degenerate triangles may lose numerical precision.

Are my entries saved?

Processing runs in your browser without a tool account or saved history. Download your result to keep a copy. Website advertising follows our privacy information.

Can I export or print it?

Copy and file download are available after generating a result. Print produces a clean copy of the visible result; use your browser’s Save as PDF option if needed.

Which angle is A?

Angle A is opposite side a, and the same naming applies to B and C. Area is expressed in squared input units and the heights use your original length unit.