# 15 18 26 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 18   c = 26

Area: T = 131.213332821
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 34.10770388766° = 34°6'25″ = 0.59552801265 rad
Angle ∠ B = β = 42.2990422069° = 42°17'26″ = 0.73881071072 rad
Angle ∠ C = γ = 103.6032539054° = 103°36'9″ = 1.80882054199 rad

Height: ha = 17.4955110428
Height: hb = 14.579925869
Height: hc = 10.09333329392

Median: ma = 21.06553744329
Median: mb = 19.22223827867
Median: mc = 10.27113192921

Inradius: r = 4.44879094309
Circumradius: R = 13.37551656477

Vertex coordinates: A[26; 0] B[0; 0] C[11.09661538462; 10.09333329392]
Centroid: CG[12.36553846154; 3.36444443131]
Coordinates of the circumscribed circle: U[13; -3.14656408097]
Coordinates of the inscribed circle: I[11.5; 4.44879094309]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 145.8932961123° = 145°53'35″ = 0.59552801265 rad
∠ B' = β' = 137.7109577931° = 137°42'34″ = 0.73881071072 rad
∠ C' = γ' = 76.39774609457° = 76°23'51″ = 1.80882054199 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.