# 9 18 23 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 18   c = 23

Area: T = 74.83331477355
Perimeter: p = 50
Semiperimeter: s = 25

Angle ∠ A = α = 21.19331307973° = 21°11'35″ = 0.37698899112 rad
Angle ∠ B = β = 46.30548463945° = 46°18'17″ = 0.80881720292 rad
Angle ∠ C = γ = 112.5022022808° = 112°30'7″ = 1.96435307132 rad

Height: ha = 16.63295883857
Height: hb = 8.31547941928
Height: hc = 6.50772302379

Median: ma = 20.15656443707
Median: mb = 14.96766295471
Median: mc = 8.38215273071

Inradius: r = 2.99333259094
Circumradius: R = 12.44876923421

Vertex coordinates: A[23; 0] B[0; 0] C[6.21773913043; 6.50772302379]
Centroid: CG[9.73991304348; 2.1699076746]
Coordinates of the circumscribed circle: U[11.5; -4.76439316371]
Coordinates of the inscribed circle: I[7; 2.99333259094]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 158.8076869203° = 158°48'25″ = 0.37698899112 rad
∠ B' = β' = 133.6955153606° = 133°41'43″ = 0.80881720292 rad
∠ C' = γ' = 67.49879771918° = 67°29'53″ = 1.96435307132 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    