# 15 25 28 triangle

### Acute scalene triangle.

Sides: a = 15   b = 25   c = 28

Area: T = 186.7732588995
Perimeter: p = 68
Semiperimeter: s = 34

Angle ∠ A = α = 32.25114533703° = 32°15'5″ = 0.56328940499 rad
Angle ∠ B = β = 62.79771055878° = 62°47'50″ = 1.09660162532 rad
Angle ∠ C = γ = 84.95114410419° = 84°57'5″ = 1.48326823505 rad

Height: ha = 24.9033011866
Height: hb = 14.94218071196
Height: hc = 13.34108992139

Median: ma = 25.46107541129
Median: mb = 18.66114576065
Median: mc = 15.13327459504

Inradius: r = 5.4933311441
Circumradius: R = 14.05545248857

Vertex coordinates: A[28; 0] B[0; 0] C[6.85771428571; 13.34108992139]
Centroid: CG[11.6199047619; 4.44769664046]
Coordinates of the circumscribed circle: U[14; 1.23767981899]
Coordinates of the inscribed circle: I[9; 5.4933311441]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 147.749854663° = 147°44'55″ = 0.56328940499 rad
∠ B' = β' = 117.2032894412° = 117°12'10″ = 1.09660162532 rad
∠ C' = γ' = 95.04985589581° = 95°2'55″ = 1.48326823505 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    