# 8 18 19 triangle

### Acute scalene triangle.

Sides: a = 8   b = 18   c = 19

Area: T = 71.68328954493
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 24.7843978051° = 24°47'2″ = 0.43325620187 rad
Angle ∠ B = β = 70.59554009401° = 70°35'43″ = 1.23221221832 rad
Angle ∠ C = γ = 84.62106210089° = 84°37'14″ = 1.47769084517 rad

Height: ha = 17.92107238623
Height: hb = 7.9654766161
Height: hc = 7.5465567942

Median: ma = 18.06993109996
Median: mb = 11.46773449412
Median: mc = 10.18657743937

Inradius: r = 3.18659064644
Circumradius: R = 9.54220252727

Vertex coordinates: A[19; 0] B[0; 0] C[2.65878947368; 7.5465567942]
Centroid: CG[7.21992982456; 2.5155189314]
Coordinates of the circumscribed circle: U[9.5; 0.89545648693]
Coordinates of the inscribed circle: I[4.5; 3.18659064644]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 155.2166021949° = 155°12'58″ = 0.43325620187 rad
∠ B' = β' = 109.405459906° = 109°24'17″ = 1.23221221832 rad
∠ C' = γ' = 95.37993789911° = 95°22'46″ = 1.47769084517 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    