# 18 19 30 triangle

### Obtuse scalene triangle.

Sides: a = 18   b = 19   c = 30

Area: T = 162.3332798596
Perimeter: p = 67
Semiperimeter: s = 33.5

Angle ∠ A = α = 34.72215542035° = 34°43'18″ = 0.60660054423 rad
Angle ∠ B = β = 36.95882263138° = 36°57'30″ = 0.64550427349 rad
Angle ∠ C = γ = 108.3220219483° = 108°19'13″ = 1.89105444765 rad

Height: ha = 18.03769776218
Height: hb = 17.08876630101
Height: hc = 10.82221865731

Median: ma = 23.44114163395
Median: mb = 22.8421847561
Median: mc = 10.84397416943

Inradius: r = 4.8465755182
Circumradius: R = 15.80108734044

Vertex coordinates: A[30; 0] B[0; 0] C[14.38333333333; 10.82221865731]
Centroid: CG[14.79444444444; 3.60773955244]
Coordinates of the circumscribed circle: U[15; -4.9676648804]
Coordinates of the inscribed circle: I[14.5; 4.8465755182]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 145.2788445796° = 145°16'42″ = 0.60660054423 rad
∠ B' = β' = 143.0421773686° = 143°2'30″ = 0.64550427349 rad
∠ C' = γ' = 71.68797805173° = 71°40'47″ = 1.89105444765 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    