# 11 20 30 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 20   c = 30

Area: T = 55.87987750403
Perimeter: p = 61
Semiperimeter: s = 30.5

Angle ∠ A = α = 10.73547526664° = 10°44'5″ = 0.18773567784 rad
Angle ∠ B = β = 19.79552089304° = 19°47'43″ = 0.3455491572 rad
Angle ∠ C = γ = 149.4770038403° = 149°28'12″ = 2.60987443032 rad

Height: ha = 10.165977728
Height: hb = 5.5887877504
Height: hc = 3.72552516694

Median: ma = 24.8954778569
Median: mb = 20.26107995894
Median: mc = 5.95881876439

Inradius: r = 1.83220909849
Circumradius: R = 29.52882063505

Vertex coordinates: A[30; 0] B[0; 0] C[10.35; 3.72552516694]
Centroid: CG[13.45; 1.24217505565]
Coordinates of the circumscribed circle: U[15; -25.43545231973]
Coordinates of the inscribed circle: I[10.5; 1.83220909849]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 169.2655247334° = 169°15'55″ = 0.18773567784 rad
∠ B' = β' = 160.205479107° = 160°12'17″ = 0.3455491572 rad
∠ C' = γ' = 30.53299615968° = 30°31'48″ = 2.60987443032 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    