# 11 15 20 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 15   c = 20

Area: T = 81.38879597975
Perimeter: p = 46
Semiperimeter: s = 23

Angle ∠ A = α = 32.86598803789° = 32°51'36″ = 0.57435131044 rad
Angle ∠ B = β = 47.72220924012° = 47°43'20″ = 0.83329076383 rad
Angle ∠ C = γ = 99.418802722° = 99°25'5″ = 1.73551719108 rad

Height: ha = 14.79878108723
Height: hb = 10.8521727973
Height: hc = 8.13987959798

Median: ma = 16.88002976164
Median: mb = 14.2921605928
Median: mc = 8.54440037453

Inradius: r = 3.53986069477
Circumradius: R = 10.13766344856

Vertex coordinates: A[20; 0] B[0; 0] C[7.4; 8.13987959798]
Centroid: CG[9.13333333333; 2.71329319933]
Coordinates of the circumscribed circle: U[10; -1.65987220067]
Coordinates of the inscribed circle: I[8; 3.53986069477]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 147.1440119621° = 147°8'24″ = 0.57435131044 rad
∠ B' = β' = 132.2787907599° = 132°16'40″ = 0.83329076383 rad
∠ C' = γ' = 80.582197278° = 80°34'55″ = 1.73551719108 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.