# 21 22 28 triangle

### Acute scalene triangle.

Sides: a = 21   b = 22   c = 28

Area: T = 228.2954628715
Perimeter: p = 71
Semiperimeter: s = 35.5

Angle ∠ A = α = 47.83551312921° = 47°50'6″ = 0.83548805392 rad
Angle ∠ B = β = 50.94223486763° = 50°56'32″ = 0.88991117131 rad
Angle ∠ C = γ = 81.22325200316° = 81°13'21″ = 1.41876004013 rad

Height: ha = 21.74223455919
Height: hb = 20.75440571559
Height: hc = 16.30767591939

Median: ma = 22.88655849827
Median: mb = 22.17697992774
Median: mc = 16.32548277173

Inradius: r = 6.43108346117
Circumradius: R = 14.1665904902

Vertex coordinates: A[28; 0] B[0; 0] C[13.23221428571; 16.30767591939]
Centroid: CG[13.7444047619; 5.4365586398]
Coordinates of the circumscribed circle: U[14; 2.16216802935]
Coordinates of the inscribed circle: I[13.5; 6.43108346117]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 132.1654868708° = 132°9'54″ = 0.83548805392 rad
∠ B' = β' = 129.0587651324° = 129°3'28″ = 0.88991117131 rad
∠ C' = γ' = 98.77774799684° = 98°46'39″ = 1.41876004013 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.