Triangle CalculatorSolve any triangle
Examples
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Pinned, kept fixedCalculated
  • Drag a corner to reshape; angles snap to 15° (hold Alt to move freely)
  • Arrow keys move a focused corner
  • Click a value to type it: Enter applies, Esc cancels, ↑ ↓ nudge, Shift ×10
  • Drag a value sideways to adjust it
  • Click a pin to keep a value fixed
  • Drag a corner to reshape; angles snap to 15°
  • Tap a value to type it, − and + step it
  • Slide a value sideways to adjust it
  • Tap a pin to keep a value fixed

Triangle calculator for sides, angles and area

Enter any three values of a triangle, at least one of them a side, and the calculator works out the rest. It handles right, acute and obtuse triangles and shows every step with the law of sines and the law of cosines.

How it works: questions and answers →