# 4 19 21 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 19   c = 21

Area: T = 34.46773758792
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 9.94988422087° = 9°56'56″ = 0.17436400533 rad
Angle ∠ B = β = 55.1550095421° = 55°9' = 0.96325507479 rad
Angle ∠ C = γ = 114.901106237° = 114°54'4″ = 2.00554018524 rad

Height: ha = 17.23436879396
Height: hb = 3.62881448294
Height: hc = 3.28326072266

Median: ma = 19.92548588452
Median: mb = 11.75879760163
Median: mc = 8.84659030065

Inradius: r = 1.56766989036
Circumradius: R = 11.57661641211

Vertex coordinates: A[21; 0] B[0; 0] C[2.28657142857; 3.28326072266]
Centroid: CG[7.76219047619; 1.09442024089]
Coordinates of the circumscribed circle: U[10.5; -4.87441743668]
Coordinates of the inscribed circle: I[3; 1.56766989036]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 170.0511157791° = 170°3'4″ = 0.17436400533 rad
∠ B' = β' = 124.8549904579° = 124°51' = 0.96325507479 rad
∠ C' = γ' = 65.09989376296° = 65°5'56″ = 2.00554018524 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.