# 4 16 19 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 16   c = 19

Area: T = 22.99986412642
Perimeter: p = 39
Semiperimeter: s = 19.5

Angle ∠ A = α = 8.7032668043° = 8°42'10″ = 0.15218902111 rad
Angle ∠ B = β = 37.24552073039° = 37°14'43″ = 0.6550051498 rad
Angle ∠ C = γ = 134.0522124653° = 134°3'8″ = 2.34396509445 rad

Height: ha = 11.49993206321
Height: hb = 2.8754830158
Height: hc = 2.42109096068

Median: ma = 17.45499283666
Median: mb = 11.15879568022
Median: mc = 6.76438746292

Inradius: r = 1.17994175007
Circumradius: R = 13.21881721741

Vertex coordinates: A[19; 0] B[0; 0] C[3.18442105263; 2.42109096068]
Centroid: CG[7.39547368421; 0.80769698689]
Coordinates of the circumscribed circle: U[9.5; -9.19107603398]
Coordinates of the inscribed circle: I[3.5; 1.17994175007]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 171.2977331957° = 171°17'50″ = 0.15218902111 rad
∠ B' = β' = 142.7554792696° = 142°45'17″ = 0.6550051498 rad
∠ C' = γ' = 45.94878753469° = 45°56'52″ = 2.34396509445 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    