Triangle Calculator
Enter any 3 sides or angles, including at least one side, and get every remaining side, angle, area, perimeter, height, median, and radius instantly. Runs entirely in your browser. Nothing you enter is ever uploaded.
Sides
Angles (degrees)
Angle A is the angle opposite side a, angle B is opposite side b, and so on. Enter any 3 values total, as long as one of them is a side.
What can you do?
TriSolve solves a triangle from any 3 known values, sides or angles, in any combination (SSS, SAS, ASA, AAS, or SSA), as long as at least one side is included. It returns every side, every angle, the perimeter, the area, the height and median from each vertex, and the inradius and circumradius, plus a diagram and a classification (equilateral, isosceles, or scalene; acute, right, or obtuse).
Got two different triangles back from the same three numbers? That's not a bug. Read Why "Two Sides and an Angle" Can Have Two Right Answers.
How it works
Every solve runs directly in your browser using the law of cosines and the law of sines, so nothing is ever sent to a server. Your 3 values are checked first: three angles alone are rejected (they fix a shape but not a size), side lengths that can't physically form a triangle are caught before solving starts, and the two-sides-plus-a-non-included-angle case (SSA) is checked for the classic "ambiguous case" where two different triangles both fit the same numbers, in which case both are shown.
Frequently asked questions
Is this free to use?
Yes. There's no sign-up and no limit on how many triangles you solve.
Do you store what I enter?
No. Every calculation happens entirely client-side in your browser. See the privacy policy for details.
How many values do I need to enter?
Exactly 3, and at least one of them has to be a side. Three angles alone tell you the triangle's shape but not its size, so there's no single answer to solve for.
Why did I get two different answers?
That happens with two sides and a non-included angle (the SSA case). Depending on the numbers, two genuinely different triangles can both satisfy the same three values, so both are shown.