# 9 19 21 triangle

### Acute scalene triangle.

Sides: a = 9   b = 19   c = 21

Area: T = 85.54996345021
Perimeter: p = 49
Semiperimeter: s = 24.5

Angle ∠ A = α = 25.37768173449° = 25°22'37″ = 0.44329090163 rad
Angle ∠ B = β = 64.79107144129° = 64°47'27″ = 1.13108112912 rad
Angle ∠ C = γ = 89.83224682422° = 89°49'57″ = 1.5687872346 rad

Height: ha = 198.9999187783
Height: hb = 98.9999615265
Height: hc = 8.14328223335

Median: ma = 19.51328163011
Median: mb = 13.06771343454
Median: mc = 10.52437825899

Inradius: r = 3.49897810001
Circumradius: R = 10.55000448859

Vertex coordinates: A[21; 0] B[0; 0] C[3.83333333333; 8.14328223335]
Centroid: CG[8.27877777778; 2.71442741112]
Coordinates of the circumscribed circle: U[10.5; 0.03107018856]
Coordinates of the inscribed circle: I[5.5; 3.49897810001]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 154.6233182655° = 154°37'23″ = 0.44329090163 rad
∠ B' = β' = 115.2099285587° = 115°12'33″ = 1.13108112912 rad
∠ C' = γ' = 90.16875317578° = 90°10'3″ = 1.5687872346 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.