Trisolve

Solve any triangle from three values and see every step, law and number used.

Trisolve works out a whole triangle from the values you already know and shows how each missing value was found, one step at a time.

Type any three of the six values (sides a, b, c and angles A, B, C), with at least one side. Trisolve recognizes the case, whether that is three sides (SSS), two sides and the angle between them (SAS), two angles and the side between them (ASA), two angles and another side (AAS), or two sides and an angle that is not between them (SSA). A separate right-triangle mode fixes angle C at 90 degrees, so two values are enough.

The SSA case needs extra care. Depending on the numbers, it gives two different triangles, exactly one, or none at all. Trisolve checks which of these applies, explains why in plain words, and when two triangles fit it draws both side by side at the same scale and lets you switch between their results and steps.

What you get for every triangle: - All three sides and all three angles, in degrees or radians - Area, perimeter, the height to each side, the inradius and the circumradius - The type: equilateral, isosceles or scalene, and acute, right or obtuse - A drawing to scale on graph paper, with the right angle marked when there is one - A steps page naming the rule behind each value (law of cosines, law of sines, angle sum, Heron's formula, Pythagoras or a right-triangle ratio) with your numbers substituted

More features: - Ten worked examples covering every case, filled in with one tap - Clear messages for impossible input: angles that add up to 180 degrees or more, sides that break the triangle inequality, a hypotenuse shorter than a leg - Choose 2 to 8 decimal places - History of your last 50 solved triangles, ready to reopen or edit - Share the results as plain text - A guide that explains the naming of sides and angles, the five cases and the ambiguous case

Trisolve is a study and checking tool for students, teachers, and anyone who measures things for a project. It needs no account and no connection: the math runs on your phone, and your history stays in the app's own storage until you clear it.

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