# 4 19 20 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 19   c = 20

Area: T = 37.56224480033
Perimeter: p = 43
Semiperimeter: s = 21.5

Angle ∠ A = α = 11.40223236093° = 11°24'8″ = 0.19990080894 rad
Angle ∠ B = β = 69.89444902121° = 69°53'40″ = 1.22198889832 rad
Angle ∠ C = γ = 98.70331861786° = 98°42'11″ = 1.7232695581 rad

Height: ha = 18.78112240016
Height: hb = 3.95439418951
Height: hc = 3.75662448003

Median: ma = 19.40436079119
Median: mb = 10.85112672071
Median: mc = 9.40774438611

Inradius: r = 1.74770906048
Circumradius: R = 10.11664865497

Vertex coordinates: A[20; 0] B[0; 0] C[1.375; 3.75662448003]
Centroid: CG[7.125; 1.25220816001]
Coordinates of the circumscribed circle: U[10; -1.5310784149]
Coordinates of the inscribed circle: I[2.5; 1.74770906048]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 168.5987676391° = 168°35'52″ = 0.19990080894 rad
∠ B' = β' = 110.1065509788° = 110°6'20″ = 1.22198889832 rad
∠ C' = γ' = 81.29768138214° = 81°17'49″ = 1.7232695581 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.