# 8 19 21 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 19   c = 21

Area: T = 75.8954663844
Perimeter: p = 48
Semiperimeter: s = 24

Angle ∠ A = α = 22.36599722153° = 22°21'36″ = 0.39902551358 rad
Angle ∠ B = β = 64.62330664748° = 64°37'23″ = 1.12878852827 rad
Angle ∠ C = γ = 93.01769613098° = 93°1'1″ = 1.62334522351 rad

Height: ha = 18.9743665961
Height: hb = 7.98989119836
Height: hc = 7.22880632232

Median: ma = 19.62114168703
Median: mb = 12.73877392029
Median: mc = 10.11218742081

Inradius: r = 3.16222776602
Circumradius: R = 10.51545732201

Vertex coordinates: A[21; 0] B[0; 0] C[3.42985714286; 7.22880632232]
Centroid: CG[8.14328571429; 2.40993544077]
Coordinates of the circumscribed circle: U[10.5; -0.55333985905]
Coordinates of the inscribed circle: I[5; 3.16222776602]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.6440027785° = 157°38'24″ = 0.39902551358 rad
∠ B' = β' = 115.3776933525° = 115°22'37″ = 1.12878852827 rad
∠ C' = γ' = 86.98330386902° = 86°58'59″ = 1.62334522351 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.