# 10 21 26 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 21   c = 26

Area: T = 99.42880518767
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 21.35986848161° = 21°21'31″ = 0.37327793739 rad
Angle ∠ B = β = 49.89219743369° = 49°53'31″ = 0.87107792225 rad
Angle ∠ C = γ = 108.7499340847° = 108°44'58″ = 1.89880340572 rad

Height: ha = 19.88656103753
Height: hb = 9.4699338274
Height: hc = 7.64883116828

Median: ma = 23.09876189249
Median: mb = 16.66658333125
Median: mc = 10.07547208398

Inradius: r = 3.48987035746
Circumradius: R = 13.72985200126

Vertex coordinates: A[26; 0] B[0; 0] C[6.44223076923; 7.64883116828]
Centroid: CG[10.81441025641; 2.54994372276]
Coordinates of the circumscribed circle: U[13; -4.41327385755]
Coordinates of the inscribed circle: I[7.5; 3.48987035746]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 158.6411315184° = 158°38'29″ = 0.37327793739 rad
∠ B' = β' = 130.1088025663° = 130°6'29″ = 0.87107792225 rad
∠ C' = γ' = 71.2510659153° = 71°15'2″ = 1.89880340572 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.