7.8 4.2 3.9 triangle

Obtuse scalene triangle.

Sides: a = 7.8   b = 4.2   c = 3.9

Area: T = 4.25657130719
Perimeter: p = 15.9
Semiperimeter: s = 7.95

Angle ∠ A = α = 148.6933027773° = 148°41'35″ = 2.59551829094 rad
Angle ∠ B = β = 16.24880921657° = 16°14'53″ = 0.28435827055 rad
Angle ∠ C = γ = 15.05988800618° = 15°3'32″ = 0.26328270387 rad

Height: ha = 1.091120848
Height: hb = 2.02765300342
Height: hc = 2.18224169599

Median: ma = 1.10222703843
Median: mb = 5.7987844427
Median: mc = 5.95329404499

Inradius: r = 0.53553098204
Circumradius: R = 7.50554402072

Vertex coordinates: A[3.9; 0] B[0; 0] C[7.48884615385; 2.18224169599]
Centroid: CG[3.79661538462; 0.727747232]
Coordinates of the circumscribed circle: U[1.95; 7.24876984419]
Coordinates of the inscribed circle: I[3.75; 0.53553098204]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 31.30769722275° = 31°18'25″ = 2.59551829094 rad
∠ B' = β' = 163.7521907834° = 163°45'7″ = 0.28435827055 rad
∠ C' = γ' = 164.9411119938° = 164°56'28″ = 0.26328270387 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     