# 5 19 21 triangle

### Obtuse scalene triangle.

Sides: a = 5   b = 19   c = 21

Area: T = 45.46663336987
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 13.17435511073° = 13°10'25″ = 0.2329921841 rad
Angle ∠ B = β = 60° = 1.04771975512 rad
Angle ∠ C = γ = 106.8266448893° = 106°49'35″ = 1.86444732614 rad

Height: ha = 18.18765334795
Height: hb = 4.7865929863
Height: hc = 4.33301270189

Median: ma = 19.86883164863
Median: mb = 11.94878031453
Median: mc = 9.09767026993

Inradius: r = 2.02107259422
Circumradius: R = 10.97696551146

Vertex coordinates: A[21; 0] B[0; 0] C[2.5; 4.33301270189]
Centroid: CG[7.83333333333; 1.4433375673]
Coordinates of the circumscribed circle: U[10.5; -3.17554264805]
Coordinates of the inscribed circle: I[3.5; 2.02107259422]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.8266448893° = 166°49'35″ = 0.2329921841 rad
∠ B' = β' = 120° = 1.04771975512 rad
∠ C' = γ' = 73.17435511073° = 73°10'25″ = 1.86444732614 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.