Geometry
Construct triangles
Three sides, two sides and an angle — build a triangle from any combination.
Give me three of the right pieces of a triangle and a compass, and I can draw exactly that triangle — no protractor. Which three pieces? SSS, SAS, or ASA.
Drag the corners
angles sum ≈ 180°
Walk through
Step 1 of 4
SSS — three sides
Draw the longest side as a base. Open the compass to side 2, arc from one end. Open to side 3, arc from the other end. Where the arcs cross is the third vertex.
Drag the triangle above and read off its sides and angles — any three values that follow SSS/SAS/ASA are enough to rebuild it from scratch.
Watch out
SSS only works if the triangle inequality holds — the two shorter sides must add up to more than the longest. Sides 2, 3, 9? The arcs never meet.