# 8 16 18 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 16   c = 18

Area: T = 63.99221870231
Perimeter: p = 42
Semiperimeter: s = 21

Angle ∠ A = α = 26.38443297494° = 26°23'4″ = 0.46604934251 rad
Angle ∠ B = β = 62.7220387264° = 62°43'13″ = 1.09546772659 rad
Angle ∠ C = γ = 90.89552829866° = 90°53'43″ = 1.58664219626 rad

Height: ha = 15.99880467558
Height: hb = 7.99990233779
Height: hc = 7.11102430026

Median: ma = 16.55329453572
Median: mb = 11.4021754251
Median: mc = 8.88881944173

Inradius: r = 3.04772470011
Circumradius: R = 9.0011098834

Vertex coordinates: A[18; 0] B[0; 0] C[3.66766666667; 7.11102430026]
Centroid: CG[7.22222222222; 2.37700810009]
Coordinates of the circumscribed circle: U[9; -0.14106421693]
Coordinates of the inscribed circle: I[5; 3.04772470011]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 153.6165670251° = 153°36'56″ = 0.46604934251 rad
∠ B' = β' = 117.2879612736° = 117°16'47″ = 1.09546772659 rad
∠ C' = γ' = 89.10547170134° = 89°6'17″ = 1.58664219626 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.