# 12 19 20 triangle

### Acute scalene triangle.

Sides: a = 12   b = 19   c = 20

Area: T = 110.9376637321
Perimeter: p = 51
Semiperimeter: s = 25.5

Angle ∠ A = α = 35.72436974884° = 35°43'25″ = 0.62334961422 rad
Angle ∠ B = β = 67.58988679538° = 67°35'20″ = 1.18796482835 rad
Angle ∠ C = γ = 76.68774345579° = 76°41'15″ = 1.33884482279 rad

Height: ha = 18.48994395534
Height: hb = 11.67875407706
Height: hc = 11.09436637321

Median: ma = 18.56107111933
Median: mb = 13.48114687627
Median: mc = 12.34990890352

Inradius: r = 4.35504563655
Circumradius: R = 10.2766136248

Vertex coordinates: A[20; 0] B[0; 0] C[4.575; 11.09436637321]
Centroid: CG[8.19216666667; 3.69878879107]
Coordinates of the circumscribed circle: U[10; 2.36662155834]
Coordinates of the inscribed circle: I[6.5; 4.35504563655]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 144.2766302512° = 144°16'35″ = 0.62334961422 rad
∠ B' = β' = 112.4111132046° = 112°24'40″ = 1.18796482835 rad
∠ C' = γ' = 103.3132565442° = 103°18'45″ = 1.33884482279 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 ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.