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Triangle Calculator
Estimate the remaining triangle values and area using the law of sines/cosines as needed.
How the Triangle Calculator Works
This triangle calculator solves triangle properties given any three known values (sides or angles). It computes the area, perimeter, and remaining unknown sides and angles using trigonometry and geometry rules.
Formula Used
Area = √[s(s − a)(s − b)(s − c)] (Heron's Formula)
Area = 0.5 × a × b × sin(C)
- a / b / c
- — the lengths of the three sides of the triangle
- s
- — semi-perimeter = (a + b + c) ÷ 2
- C
- — the angle opposite side c, in degrees
Example Calculation
For a triangle with side lengths a = 3, b = 4, and c = 5: s = (3+4+5)/2 = 6. Area = √[6 × (6-3) × (6-4) × (6-5)] = √[6 × 3 × 2 × 1] = √36 = 6. The perimeter is 3 + 4 + 5 = 12.