# 4 25 28 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 25   c = 28

Area: T = 34.9566222622
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 5.73219679652° = 5°43'55″ = 0.11000417136 rad
Angle ∠ B = β = 38.62548328731° = 38°37'29″ = 0.67441305067 rad
Angle ∠ C = γ = 135.6433199162° = 135°38'36″ = 2.36774204333 rad

Height: ha = 17.4788111311
Height: hb = 2.79664978098
Height: hc = 2.49768730444

Median: ma = 26.46769605357
Median: mb = 15.6122494996
Median: mc = 11.15879568022

Inradius: r = 1.22765341271
Circumradius: R = 20.02550469729

Vertex coordinates: A[28; 0] B[0; 0] C[3.125; 2.49768730444]
Centroid: CG[10.375; 0.83222910148]
Coordinates of the circumscribed circle: U[14; -14.31879085856]
Coordinates of the inscribed circle: I[3.5; 1.22765341271]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 174.2688032035° = 174°16'5″ = 0.11000417136 rad
∠ B' = β' = 141.3755167127° = 141°22'31″ = 0.67441305067 rad
∠ C' = γ' = 44.35768008383° = 44°21'24″ = 2.36774204333 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    