# 15 20 26 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 20   c = 26

Area: T = 149.4577142686
Perimeter: p = 61
Semiperimeter: s = 30.5

Angle ∠ A = α = 35.08880894599° = 35°5'17″ = 0.61224026893 rad
Angle ∠ B = β = 50.03658856705° = 50°2'9″ = 0.87332909491 rad
Angle ∠ C = γ = 94.87660248696° = 94°52'34″ = 1.65658990152 rad

Height: ha = 19.92876190249
Height: hb = 14.94657142686
Height: hc = 11.49767032836

Median: ma = 21.94988040676
Median: mb = 18.72216452268
Median: mc = 11.97991485507

Inradius: r = 4.99002341864
Circumradius: R = 13.047721852

Vertex coordinates: A[26; 0] B[0; 0] C[9.63546153846; 11.49767032836]
Centroid: CG[11.87882051282; 3.83222344279]
Coordinates of the circumscribed circle: U[13; -1.10990135742]
Coordinates of the inscribed circle: I[10.5; 4.99002341864]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 144.912191054° = 144°54'43″ = 0.61224026893 rad
∠ B' = β' = 129.964411433° = 129°57'51″ = 0.87332909491 rad
∠ C' = γ' = 85.12439751304° = 85°7'26″ = 1.65658990152 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.