TC
Triangle Calculator
Enter any 3 known sides/angles — instantly solve for the triangle's remaining sides, angles and area.
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Enter any 3 values (sides/angles)
Result
Side a / b / c—
Angle A / B / C—
Area—
Perimeter—
Type—
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How to use — Triangle Calculator
- Enter any 3 values — any combination of sides or angles (SSS, SAS, ASA, AAS).
- The remaining sides/angles, area, perimeter, and triangle type (equilateral/isosceles/scalene, right/acute/obtuse) are computed instantly.
FAQ
Which combinations work?
SSS (all three sides), SAS (2 sides + the angle between them), ASA (2 angles + the side between them), AAS (2 angles + any side). SSA can be ambiguous.
How is the area calculated?
With 3 sides, Heron's Formula is used. With an angle+sides combination, trigonometry (½ab×sinC) is used.
Why do I get an "Invalid triangle" error?
By the triangle inequality, the sum of any 2 sides must exceed the third, and the angles must sum to 180° — if either is violated, a triangle can't exist.
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