Method
For SSS data, angles come from the cosine law. Area uses Heron's formula K = √[s(s−a)(s−b)(s−c)] where s is the semiperimeter.
Math worksheet
Triangle Calculator
Solve a general triangle from three sides using the cosine law and Heron's formula, then inspect angles, heights, radii and classification.
The calculation runs locally. Exact-integer tools avoid floating point; decimal and transcendental tools report rounding limits.
Method and verification guide
How the Triangle Calculator works
For SSS data, angles come from the cosine law. Area uses Heron's formula K = √[s(s−a)(s−b)(s−c)] where s is the semiperimeter. The calculator keeps the intermediate values visible so you can reproduce the answer independently.
Interpret the result
The largest angle lies opposite the longest side; side and angle classifications summarize the triangle's shape.
Check the assumptions
This page assumes Euclidean plane geometry and three measured side lengths; diagrams and rounded classifications are illustrative.
Local calculation
Everything runs in this browser. Inputs are not sent to an external calculator.
Rounding
Displayed values may be rounded for readability while calculations use full floating-point precision unless the tool explicitly uses exact integers.
Scope
This page assumes Euclidean plane geometry and three measured side lengths; diagrams and rounded classifications are illustrative.
Simple by design
Three steps to a clearer number.
Enter your details
Use realistic values in each field. You can change them anytime.
Calculate instantly
The formula runs locally, so there is no account or waiting time.
Use the result
Treat the answer as a practical estimate for your next decision.