Triangle Calculator
GeometryArea, perimeter, angles and height
Quick Answer
Triangle Calculator: Area, perimeter, angles and height. Area = base × height ÷ 2.
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How to Use
- Enter known values: fill sides, radius or angles in the Triangle Calculator.
- Auto-solve the rest: all unknowns are solved instantly — no manual derivation.
- See formula and steps: the result panel shows the formula used and the substitution.
- Try another case: change any known value to solve again.
Key Points
- Triangle Calculator is a free online geometry tool — open and use, no sign-up.
- All calculations run locally in your browser; your data never leaves the device.
- Key capability: Area, perimeter, angles and height.
- Results come with formulas and reference tables so you can verify every number.
Formula & How It Works
Triangle formulas
Area = base × height ÷ 2
Heron: A = √[s(s−a)(s−b)(s−c)], s = (a+b+c)÷2
FAQ
How do I use the Triangle Calculator?
Open the page and fill in the input fields — results update automatically. Area, perimeter, angles and height.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.
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Source & Updates
Based on standard Euclidean geometry formulas. Last updated: 2025-07
Last updated:
Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.
Cite this page: YiJianSuan. Triangle Calculator[EB/OL]. https://www.yijiansuan.com/en/c/geometry/triangle
Results provided by this tool are for reference only and do not constitute professional advice.