# 6 15 20 triangle

### Obtuse scalene triangle.

Sides: a = 6   b = 15   c = 20

Area: T = 28.59108639254
Perimeter: p = 41
Semiperimeter: s = 20.5

Angle ∠ A = α = 10.98881377331° = 10°59'17″ = 0.19217791821 rad
Angle ∠ B = β = 28.45879982553° = 28°27'29″ = 0.49766857681 rad
Angle ∠ C = γ = 140.5543864012° = 140°33'14″ = 2.45331277034 rad

Height: ha = 9.53302879751
Height: hb = 3.81221151901
Height: hc = 2.85990863925

Median: ma = 17.42112513902
Median: mb = 12.7188097342
Median: mc = 5.52326805086

Inradius: r = 1.3954676289
Circumradius: R = 15.73992935441

Vertex coordinates: A[20; 0] B[0; 0] C[5.275; 2.85990863925]
Centroid: CG[8.425; 0.95330287975]
Coordinates of the circumscribed circle: U[10; -12.15442322368]
Coordinates of the inscribed circle: I[5.5; 1.3954676289]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 169.0121862267° = 169°43″ = 0.19217791821 rad
∠ B' = β' = 151.5422001745° = 151°32'31″ = 0.49766857681 rad
∠ C' = γ' = 39.44661359884° = 39°26'46″ = 2.45331277034 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.