# 2 18 19 triangle

### Obtuse scalene triangle.

Sides: a = 2   b = 18   c = 19

Area: T = 15.99880467558
Perimeter: p = 39
Semiperimeter: s = 19.5

Angle ∠ A = α = 5.36882046992° = 5°22'6″ = 0.09436928469 rad
Angle ∠ B = β = 57.35221825649° = 57°21'8″ = 1.0010984419 rad
Angle ∠ C = γ = 117.2879612736° = 117°16'47″ = 2.04769153877 rad

Height: ha = 15.99880467558
Height: hb = 1.77875607506
Height: hc = 1.68440049217

Median: ma = 18.48797186126
Median: mb = 10.07547208398
Median: mc = 8.58877820187

Inradius: r = 0.82204126541
Circumradius: R = 10.68988048654

Vertex coordinates: A[19; 0] B[0; 0] C[1.07989473684; 1.68440049217]
Centroid: CG[6.69329824561; 0.56113349739]
Coordinates of the circumscribed circle: U[9.5; -4.89990355633]
Coordinates of the inscribed circle: I[1.5; 0.82204126541]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 174.6321795301° = 174°37'54″ = 0.09436928469 rad
∠ B' = β' = 122.6487817435° = 122°38'52″ = 1.0010984419 rad
∠ C' = γ' = 62.7220387264° = 62°43'13″ = 2.04769153877 rad

# How did we calculate this triangle?

Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS. ### 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    