# 7 19 21 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 19   c = 21

Area: T = 66.04768583659
Perimeter: p = 47
Semiperimeter: s = 23.5

Angle ∠ A = α = 19.3333244003° = 19°20' = 0.33774287629 rad
Angle ∠ B = β = 63.97442200559° = 63°58'27″ = 1.11765607764 rad
Angle ∠ C = γ = 96.69325359412° = 96°41'33″ = 1.68876031143 rad

Height: ha = 18.87105309617
Height: hb = 6.95223008806
Height: hc = 6.29901769872

Median: ma = 19.71767441531
Median: mb = 12.44398553046
Median: mc = 9.7343961167

Inradius: r = 2.81105046113
Circumradius: R = 10.57220395682

Vertex coordinates: A[21; 0] B[0; 0] C[3.07114285714; 6.29901769872]
Centroid: CG[8.02438095238; 2.09767256624]
Coordinates of the circumscribed circle: U[10.5; -1.23220797993]
Coordinates of the inscribed circle: I[4.5; 2.81105046113]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 160.6676755997° = 160°40' = 0.33774287629 rad
∠ B' = β' = 116.0265779944° = 116°1'33″ = 1.11765607764 rad
∠ C' = γ' = 83.30774640588° = 83°18'27″ = 1.68876031143 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.