# 8 11 15 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 11   c = 15

Area: T = 42.84985705713
Perimeter: p = 34
Semiperimeter: s = 17

Angle ∠ A = α = 31.29904452139° = 31°17'26″ = 0.54661212934 rad
Angle ∠ B = β = 45.57329959992° = 45°34'23″ = 0.79553988302 rad
Angle ∠ C = γ = 103.1376558787° = 103°8'12″ = 1.880007253 rad

Height: ha = 10.71221426428
Height: hb = 7.79106491948
Height: hc = 5.71331427428

Median: ma = 12.53299640861
Median: mb = 10.68987791632
Median: mc = 6.02107972894

Inradius: r = 2.52105041513
Circumradius: R = 7.70215404622

Vertex coordinates: A[15; 0] B[0; 0] C[5.6; 5.71331427428]
Centroid: CG[6.86766666667; 1.90443809143]
Coordinates of the circumscribed circle: U[7.5; -1.7550350105]
Coordinates of the inscribed circle: I[6; 2.52105041513]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.7109554786° = 148°42'34″ = 0.54661212934 rad
∠ B' = β' = 134.4277004001° = 134°25'37″ = 0.79553988302 rad
∠ C' = γ' = 76.86334412131° = 76°51'48″ = 1.880007253 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    