# 7 21 26 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 21   c = 26

Area: T = 56.9210997883
Perimeter: p = 54
Semiperimeter: s = 27

Angle ∠ A = α = 12.03545697281° = 12°2'4″ = 0.21100428658 rad
Angle ∠ B = β = 38.71992973222° = 38°43'9″ = 0.67657792223 rad
Angle ∠ C = γ = 129.246613295° = 129°14'46″ = 2.25657705654 rad

Height: ha = 16.26331422523
Height: hb = 5.42110474174
Height: hc = 4.37985382987

Median: ma = 23.3721991785
Median: mb = 15.88223801743
Median: mc = 8.71877978871

Inradius: r = 2.10881851068
Circumradius: R = 16.78664239127

Vertex coordinates: A[26; 0] B[0; 0] C[5.46215384615; 4.37985382987]
Centroid: CG[10.48771794872; 1.46595127662]
Coordinates of the circumscribed circle: U[13; -10.62199824754]
Coordinates of the inscribed circle: I[6; 2.10881851068]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.9655430272° = 167°57'56″ = 0.21100428658 rad
∠ B' = β' = 141.2810702678° = 141°16'51″ = 0.67657792223 rad
∠ C' = γ' = 50.75438670503° = 50°45'14″ = 2.25657705654 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.