# 8 15 20 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 15   c = 20

Area: T = 53.19771568789
Perimeter: p = 43
Semiperimeter: s = 21.5

Angle ∠ A = α = 20.77218550453° = 20°46'19″ = 0.36325372623 rad
Angle ∠ B = β = 41.68795989952° = 41°40'47″ = 0.72774462334 rad
Angle ∠ C = γ = 117.5498545959° = 117°32'55″ = 2.05216091579 rad

Height: ha = 13.29992892197
Height: hb = 7.09329542505
Height: hc = 5.32197156879

Median: ma = 17.21991753577
Median: mb = 13.25770735836
Median: mc = 6.67108320321

Inradius: r = 2.47442863665
Circumradius: R = 11.27987982517

Vertex coordinates: A[20; 0] B[0; 0] C[5.975; 5.32197156879]
Centroid: CG[8.65883333333; 1.77332385626]
Coordinates of the circumscribed circle: U[10; -5.21664441914]
Coordinates of the inscribed circle: I[6.5; 2.47442863665]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 159.2288144955° = 159°13'41″ = 0.36325372623 rad
∠ B' = β' = 138.3220401005° = 138°19'13″ = 0.72774462334 rad
∠ C' = γ' = 62.45114540405° = 62°27'5″ = 2.05216091579 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.