Solve a triangle from three measurements

The job

Trusses, braces, ramp angles, camera sight-lines — a surprising amount of practical measuring reduces to finishing a triangle. Three known parts (with at least one side) fix the whole triangle; this does the trig.

How to do it

Pick the combination you measured — three sides, two sides with the angle between them, two angles with a side, or two sides with a non-included angle — and enter the values. The result lists all three sides, all three angles, and the area.

• Angles are entered and shown in degrees, not radians.
• The two-sides-plus-outside-angle case can genuinely produce two different triangles; when both exist, both are shown.
• Use one unit for all sides — the area comes out in square units of it.

Worked example

Two fence rails of 2 m and 3 m meeting at 60°: choose two-sides-plus-included-angle, enter 2, 3, 60 — the closing side is √7 ≈ 2.646 m, angles come out to about 40.9° and 79.1°, and the panel area is 2.598 m².

Limits

Flat triangles only — nothing spherical. Impossible inputs (a side longer than the other two combined, angles summing past 180°) are rejected rather than fudged. Results round to a few decimals; check tolerances before cutting expensive stock.