# 6 18 19 triangle

### Obtuse scalene triangle.

Sides: a = 6   b = 18   c = 19

Area: T = 53.99994212932
Perimeter: p = 43
Semiperimeter: s = 21.5

Angle ∠ A = α = 18.40882758102° = 18°24'30″ = 0.32112850225 rad
Angle ∠ B = β = 71.32664650038° = 71°19'35″ = 1.24548816581 rad
Angle ∠ C = γ = 90.26552591861° = 90°15'55″ = 1.5755425973 rad

Height: ha = 187.9998070977
Height: hb = 65.9999356992
Height: hc = 5.68441496098

Median: ma = 18.26219823677
Median: mb = 10.84397416943
Median: mc = 9.47436476607

Inradius: r = 2.51216009904
Circumradius: R = 9.55001018106

Vertex coordinates: A[19; 0] B[0; 0] C[1.92110526316; 5.68441496098]
Centroid: CG[6.97436842105; 1.89547165366]
Coordinates of the circumscribed circle: U[9.5; -0.04439819528]
Coordinates of the inscribed circle: I[3.5; 2.51216009904]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 161.592172419° = 161°35'30″ = 0.32112850225 rad
∠ B' = β' = 108.6743534996° = 108°40'25″ = 1.24548816581 rad
∠ C' = γ' = 89.73547408139° = 89°44'5″ = 1.5755425973 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    