# 12 24 28 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 24   c = 28

Area: T = 143.108835056
Perimeter: p = 64
Semiperimeter: s = 32

Angle ∠ A = α = 25.20987652968° = 25°12'32″ = 0.44399759548 rad
Angle ∠ B = β = 58.41218644948° = 58°24'43″ = 1.01994793577 rad
Angle ∠ C = γ = 96.37993702084° = 96°22'46″ = 1.68221373411 rad

Height: ha = 23.851139176
Height: hb = 11.926569588
Height: hc = 10.222202504

Median: ma = 25.37771550809
Median: mb = 17.889854382
Median: mc = 12.80662484749

Inradius: r = 4.4722135955
Circumradius: R = 14.08772282582

Vertex coordinates: A[28; 0] B[0; 0] C[6.28657142857; 10.222202504]
Centroid: CG[11.42985714286; 3.407734168]
Coordinates of the circumscribed circle: U[14; -1.56552475842]
Coordinates of the inscribed circle: I[8; 4.4722135955]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 154.7911234703° = 154°47'28″ = 0.44399759548 rad
∠ B' = β' = 121.5888135505° = 121°35'17″ = 1.01994793577 rad
∠ C' = γ' = 83.62106297916° = 83°37'14″ = 1.68221373411 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    