Find missing sides and angles with trusted formulas. Review area, perimeter, heights, and triangle classification. Download reports, inspect graphs, and learn each solving method.
Use SSS for three sides. Use SAS for two sides with the included angle. Use ASA or AAS for two angles and one side. Use RHS for right triangles.
| Mode | Known values | Sample input | Main output |
|---|---|---|---|
| SSS | Three sides | a = 7, b = 8, c = 9 | All angles, area, perimeter |
| SAS | Two sides and included angle | b = 10, c = 12, A = 40 | Missing side and remaining angles |
| ASA / AAS | Two angles and one side | A = 50, B = 60, a = 9 | Remaining side lengths and angle C |
| RHS | Right triangle data | C = 90, A = 35, c = 15 | Legs, acute angle, area |
Use this when three sides are known, or when two sides with the included angle are known.
a² = b² + c² − 2bc cos(A)
b² = a² + c² − 2ac cos(B)
c² = a² + b² − 2ab cos(C)
Use this when one side and its opposite angle are known, together with other angle data.
a / sin(A) = b / sin(B) = c / sin(C)
The interior angles of every triangle add to 180 degrees.
A + B + C = 180
For right triangles, the Pythagorean theorem links the legs and hypotenuse.
hypotenuse² = leg₁² + leg₂²
Heron’s formula is useful after all three sides are known.
Area = √[s(s − a)(s − b)(s − c)]
s = (a + b + c) / 2
Choose the solving mode that matches your available data. Enter only the values needed for that mode. Use side labels a, b, and c opposite angles A, B, and C. For a right triangle, select which angle is 90 degrees. Then press the calculate button.
The result section appears above the form. It shows solved sides, angles, area, perimeter, heights, medians, and triangle classification. The solution steps explain which rule was used first. The graph then plots the solved triangle with simple coordinates.
Use the export buttons to save your result table as CSV or PDF. The example data table can help you test the page quickly. Increase decimal places when you need more precision for study, checking homework, drafting, or engineering estimates.
SSS means side, side, side. You already know all three side lengths. The calculator then finds every angle and all related triangle measurements.
SAS means side, angle, side. The angle must be between the two known sides. That lets the calculator use the Law of Cosines correctly.
Use ASA or AAS when you know two angles and one side. The tool first finds the third angle, then uses the Law of Sines.
RHS is for right triangles. One angle is fixed at 90 degrees. You can solve it with two sides or with one acute angle and one side.
That is a basic triangle rule in Euclidean geometry. If your entered angles do not fit that rule, the triangle is invalid and cannot be solved.
Yes. After the triangle is solved, the page calculates area, perimeter, semi perimeter, heights, medians, inradius, and circumradius automatically.
The page checks for impossible triangles, such as bad side lengths or invalid angle totals. It then shows a clear message instead of incorrect results.
The graph gives a quick visual check. It helps confirm the solved shape, compare side balance, and support classroom explanation or report screenshots.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.