Triangle Calculator

Triangle Calculator – Quick Cheat Sheet

• Valid inputs: SSS (3 sides), SAS (2 sides + included angle), or ASA/AAS (2 angles + 1 side).
• Law of Cosines: a² = b² + c² − 2bc·cos(A), similarly for b², c².
• Law of Sines: a/sin(A) = b/sin(B) = c/sin(C).
• Area: Heron’s formula √[s(s−a)(s−b)(s−c)], or ½ab·sin(C) when SAS.
• Radii: inradius r = 2·Area / p, circumradius R = a / (2·sin(A)).
• Heights: hₐ = 2·Area / a (and cyclic).
• SSA note: The “two sides + non-included angle” case can yield 0/1/2 solutions (ambiguous) and is not auto-solved here.
• Right triangles: one angle is 90°; Pythagoras holds: a²+b²=c² (with C=90° opposite side c).