# 8 12 18 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 12   c = 18

Area: T = 38.24991829978
Perimeter: p = 38
Semiperimeter: s = 19

Angle ∠ A = α = 20.74219164807° = 20°44'31″ = 0.36220147358 rad
Angle ∠ B = β = 32.08991838633° = 32°5'21″ = 0.56600619127 rad
Angle ∠ C = γ = 127.1698899656° = 127°10'8″ = 2.22195160051 rad

Height: ha = 9.56222957495
Height: hb = 6.3754863833
Height: hc = 4.2549909222

Median: ma = 14.76548230602
Median: mb = 12.576980509
Median: mc = 4.79658315233

Inradius: r = 2.01331148946
Circumradius: R = 11.29443588893

Vertex coordinates: A[18; 0] B[0; 0] C[6.77877777778; 4.2549909222]
Centroid: CG[8.25992592593; 1.41766364073]
Coordinates of the circumscribed circle: U[9; -6.82436751623]
Coordinates of the inscribed circle: I[7; 2.01331148946]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 159.2588083519° = 159°15'29″ = 0.36220147358 rad
∠ B' = β' = 147.9110816137° = 147°54'39″ = 0.56600619127 rad
∠ C' = γ' = 52.8311100344° = 52°49'52″ = 2.22195160051 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 ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.