Triangle calculator SSS - result

Please enter the triangle sides:

Obtuse scalene triangle.

Sides: a = 5   b = 9   c = 12

Area: T = 20.39660780544
Perimeter: p = 26
Semiperimeter: s = 13

Angle ∠ A = α = 22.19216065663° = 22°11'30″ = 0.38773166009 rad
Angle ∠ B = β = 42.83334280661° = 42°50' = 0.74875843497 rad
Angle ∠ C = γ = 114.9754965368° = 114°58'30″ = 2.0076691703 rad

Height: ha = 8.15884312217
Height: hb = 4.53224617899
Height: hc = 3.39993463424

Median: ma = 10.3087764064
Median: mb = 8.01656097709
Median: mc = 4.12331056256

Inradius: r = 1.56989290811
Circumradius: R = 6.61989195609

Vertex coordinates: A[12; 0] B[0; 0] C[3.66766666667; 3.39993463424]
Centroid: CG[5.22222222222; 1.13331154475]
Coordinates of the circumscribed circle: U[6; -2.79546549257]
Coordinates of the inscribed circle: I[4; 1.56989290811]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.8088393434° = 157°48'30″ = 0.38773166009 rad
∠ B' = β' = 137.1676571934° = 137°10' = 0.74875843497 rad
∠ C' = γ' = 65.02550346323° = 65°1'30″ = 2.0076691703 rad

How did we calculate this triangle?

1. The triangle circumference is the sum of the lengths of its three sides 2. Semiperimeter of the triangle 3. The triangle area using Heron's formula 4. Calculate the heights of the triangle from its area. 5. Calculation of the inner angles of the triangle using a Law of Cosines    