# 9 15 20 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 15   c = 20

Area: T = 63.27771680782
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 24.95113010927° = 24°57'5″ = 0.43554823567 rad
Angle ∠ B = β = 44.67546095644° = 44°40'29″ = 0.78797190289 rad
Angle ∠ C = γ = 110.3744089343° = 110°22'27″ = 1.92663912679 rad

Height: ha = 14.06215929063
Height: hb = 8.43769557438
Height: hc = 6.32877168078

Median: ma = 17.09553209973
Median: mb = 13.57438719605
Median: mc = 7.28801098893

Inradius: r = 2.87662349126
Circumradius: R = 10.66773547584

Vertex coordinates: A[20; 0] B[0; 0] C[6.4; 6.32877168078]
Centroid: CG[8.8; 2.10992389359]
Coordinates of the circumscribed circle: U[10; -3.71438198048]
Coordinates of the inscribed circle: I[7; 2.87662349126]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 155.0498698907° = 155°2'55″ = 0.43554823567 rad
∠ B' = β' = 135.3255390436° = 135°19'31″ = 0.78797190289 rad
∠ C' = γ' = 69.62659106571° = 69°37'33″ = 1.92663912679 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.