# 12 19 28 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 19   c = 28

Area: T = 90.17217111959
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 19.81554363505° = 19°48'56″ = 0.3465844607 rad
Angle ∠ B = β = 32.46217449672° = 32°27'42″ = 0.56765643306 rad
Angle ∠ C = γ = 127.7232818682° = 127°43'22″ = 2.22991837159 rad

Height: ha = 15.02986185327
Height: hb = 9.49217590733
Height: hc = 6.4410836514

Median: ma = 23.16224696438
Median: mb = 19.33326149292
Median: mc = 7.51766481892

Inradius: r = 3.05766681761
Circumradius: R = 17.76995642961

Vertex coordinates: A[28; 0] B[0; 0] C[10.125; 6.4410836514]
Centroid: CG[12.70883333333; 2.14769455047]
Coordinates of the circumscribed circle: U[14; -10.82993386812]
Coordinates of the inscribed circle: I[10.5; 3.05766681761]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 160.185456365° = 160°11'4″ = 0.3465844607 rad
∠ B' = β' = 147.5388255033° = 147°32'18″ = 0.56765643306 rad
∠ C' = γ' = 52.27771813177° = 52°16'38″ = 2.22991837159 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    