A triangle solver finds all unknowns from 3 known values. With 3 sides (SSS), use the law of cosines for angles. With 2 sides and included angle (SAS), use law of cosines for the third side. With angles and a side (ASA/AAS), use law of sines. Area can be found by Hero's formula: √(s(s-a)(s-b)(s-c)) where s is the semi-perimeter.
How to Use
Enter 3 known values (at least 1 side):
- Sides: a, b, c
- Angles: A, B, C (degrees)
- Solve: All unknowns computed
Key Formulas
- Law of Cosines: c² = a² + b² − 2ab·cos(C)
- Law of Sines: a/sin(A) = b/sin(B) = c/sin(C)
- Hero's: Area = √(s(s-a)(s-b)(s-c))
Triangle Types
- Equilateral: all sides equal
- Isosceles: two sides equal
- Scalene: all sides different
- Right: one 90° angle
- Obtuse: one angle > 90°
- Acute: all angles < 90°
Step-by-Step Instructions
- 1Enter 3 known values.
- 2Select the configuration type.
- 3View all solved values.
- 4Check the triangle classification.
- 5Review area and perimeter.