# 13 20 26 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 20   c = 26

Area: T = 127.218807065
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 29.29546008376° = 29°17'41″ = 0.51112872377 rad
Angle ∠ B = β = 48.83108663768° = 48°49'51″ = 0.85222593949 rad
Angle ∠ C = γ = 101.8754532786° = 101°52'28″ = 1.7788046021 rad

Height: ha = 19.57220108693
Height: hb = 12.7221807065
Height: hc = 9.78660054346

Median: ma = 22.26554440782
Median: mb = 17.95882849961
Median: mc = 10.74770926301

Inradius: r = 4.31224769712
Circumradius: R = 13.28442762931

Vertex coordinates: A[26; 0] B[0; 0] C[8.55876923077; 9.78660054346]
Centroid: CG[11.51992307692; 3.26220018115]
Coordinates of the circumscribed circle: U[13; -2.73334953142]
Coordinates of the inscribed circle: I[9.5; 4.31224769712]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 150.7055399162° = 150°42'19″ = 0.51112872377 rad
∠ B' = β' = 131.1699133623° = 131°10'9″ = 0.85222593949 rad
∠ C' = γ' = 78.12554672144° = 78°7'32″ = 1.7788046021 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.