answer : 12.9 units
explanation :
Sides: a = 7.616 b = 7.211 c = 13.038
Area: T = 23
Perimeter: p = 27.865
Semiperimeter: s = 13.933
Angle ∠ A = α = 29.291° = 29°17'29″ = 0.511 rad
Angle ∠ B = β = 27.597° = 27°35'50″ = 0.482 rad
Angle ∠ C = γ = 123.111° = 123°6'41″ = 2.149 rad
Height: ha = 6.04
Height: hb = 6.379
Height: hc = 3.528
Median: ma = 9.823
Median: mb = 10.05
Median: mc = 3.536
Inradius: r = 1.651
Circumradius: R = 7.783
Vertex coordinates: A[3; -1] B[16; -2] C[9; -5]
Centroid: CG[9.333; -2.667]
Coordinates of the circumscribed circle: U[0; 0]
Coordinates of the inscribed circle: I[3.158; 1.651]
Exterior (or external, outer) angles of the triangle:
∠ A' = α' = 150.709° = 150°42'31″ = 0.511 rad
∠ B' = β' = 152.403° = 152°24'10″ = 0.482 rad
∠ C' = γ' = 56.889° = 56°53'19″ = 2.149 rad