# 12.8 11.4 3.3 triangle

### Obtuse scalene triangle.

Sides: a = 12.8   b = 11.4   c = 3.3

Area: T = 17.91103976435
Perimeter: p = 27.5
Semiperimeter: s = 13.75

Angle ∠ A = α = 107.7921590573° = 107°47'30″ = 1.88113181615 rad
Angle ∠ B = β = 57.99880641654° = 57°59'53″ = 1.01222571795 rad
Angle ∠ C = γ = 14.21103452616° = 14°12'37″ = 0.24880173127 rad

Height: ha = 2.79884996318
Height: hb = 3.14221750252
Height: hc = 10.85547864506

Median: ma = 5.42881672782
Median: mb = 7.4087766195
Median: mc = 12.00773935556

Inradius: r = 1.30325743741
Circumradius: R = 6.72114588082

Vertex coordinates: A[3.3; 0] B[0; 0] C[6.78333333333; 10.85547864506]
Centroid: CG[3.36111111111; 3.61882621502]
Coordinates of the circumscribed circle: U[1.65; 6.51657891702]
Coordinates of the inscribed circle: I[2.35; 1.30325743741]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 72.2088409427° = 72°12'30″ = 1.88113181615 rad
∠ B' = β' = 122.0021935835° = 122°7″ = 1.01222571795 rad
∠ C' = γ' = 165.7989654738° = 165°47'23″ = 0.24880173127 rad

# How did we calculate this triangle?

### 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    