About Triangle Calculator

A triangle is a polygon with three edges and three vertices. Triangles are fundamental in geometry and have many properties and formulas. This calculator can solve triangles given any combination of three values (at least one side), using the Law of Sines, Law of Cosines, and Heron's formula. It computes all unknown sides, angles, area, perimeter, medians, inradius, and circumradius.

• Law of Sines: a/sin(A) = b/sin(B) = c/sin(C). Useful for finding unknowns when given two angles and one side (AAS or ASA), or two sides and a non-included angle (SSA).
• Law of Cosines: c² = a² + b² - 2ab·cos(C). Useful for SSS and SAS cases.
• Heron's Formula: Area = √[s(s-a)(s-b)(s-c)], where s = (a+b+c)/2.
• Median: The length from a vertex to the midpoint of the opposite side. ma = 0.5√(2b²+2c²−a²).
• Inradius: r = Area/s, the radius of the inscribed circle.
• Circumradius: R = a/(2sin(A)), the radius of the circumscribed circle.

Triangles are classified by their sides (equilateral, isosceles, scalene) and angles (acute, right, obtuse). The sum of interior angles is always 180°. The area can be found using base and height, two sides and the included angle, or all three sides. Medians, inradius, and circumradius are important triangle centers.