# 19 20 25 triangle

### Acute scalene triangle.

Sides: a = 19   b = 20   c = 25

Area: T = 186.9333143129
Perimeter: p = 64
Semiperimeter: s = 32

Angle ∠ A = α = 48.39443462161° = 48°23'40″ = 0.84546406808 rad
Angle ∠ B = β = 51.9144106787° = 51°54'51″ = 0.90660720917 rad
Angle ∠ C = γ = 79.69215469969° = 79°41'30″ = 1.39108798811 rad

Height: ha = 19.67771729609
Height: hb = 18.69333143129
Height: hc = 14.95546514503

Median: ma = 20.5498722588
Median: mb = 19.82442276016
Median: mc = 14.97549791319

Inradius: r = 5.84216607228
Circumradius: R = 12.70550771214

Vertex coordinates: A[25; 0] B[0; 0] C[11.72; 14.95546514503]
Centroid: CG[12.24; 4.98548838168]
Coordinates of the circumscribed circle: U[12.5; 2.27435401165]
Coordinates of the inscribed circle: I[12; 5.84216607228]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 131.6065653784° = 131°36'20″ = 0.84546406808 rad
∠ B' = β' = 128.0865893213° = 128°5'9″ = 0.90660720917 rad
∠ C' = γ' = 100.3088453003° = 100°18'30″ = 1.39108798811 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    