Triangle solver
Three known values solve the triangle — this page does the law of sines and cosines for you. Give it any valid combination (two sides and an angle, three sides, two angles and a side) and it returns every side, every angle, and the area. It flags the ambiguous SSA case where two triangles fit the data, instead of silently picking one.
The everyday uses: taper angles from measured offsets, dovetail widths over pins, chamfer edge breaks, and any layout where the print gives you one description of a corner and inspection needs another.
Angles: decimal or DMS (12°30′)
Enter exactly two known values for the right triangle, with at least one side.
How it’s calculated
Right triangles use c² = a² + b² and trig ratios; oblique triangles use the laws of sines and cosines, and area = ½ab·sin C.
When do machinists solve a triangle?
Any three known parts of a triangle — as long as one is a side — determine one or more candidate solutions, and the law of sines and cosines return them. On the shop floor that comes up constantly: a taper angle from measured offsets, a dovetail width over pins, a chamfer edge break, or converting a corner the print describes one way and inspection needs another.
Enter any valid combination (SSS, SAS, ASA, or SSA) and the solver returns every side, every angle, and the area. The SSA case can fit two different triangles; the solver returns both rather than silently choosing one, so you decide which matches the part in front of you.