# 8 9 13 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 9   c = 13

Area: T = 35.49664786986
Perimeter: p = 30
Semiperimeter: s = 15

Angle ∠ A = α = 37.35768519729° = 37°21'25″ = 0.65220000651 rad
Angle ∠ B = β = 43.04990798002° = 43°2'57″ = 0.75113481825 rad
Angle ∠ C = γ = 99.59440682269° = 99°35'39″ = 1.7388244406 rad

Height: ha = 8.87441196746
Height: hb = 7.88881063775
Height: hc = 5.46109967229

Median: ma = 10.44403065089
Median: mb = 9.81107084352
Median: mc = 5.5

Inradius: r = 2.36664319132
Circumradius: R = 6.59222031869

Vertex coordinates: A[13; 0] B[0; 0] C[5.84661538462; 5.46109967229]
Centroid: CG[6.28220512821; 1.8220332241]
Coordinates of the circumscribed circle: U[6.5; -1.09987005311]
Coordinates of the inscribed circle: I[6; 2.36664319132]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 142.6433148027° = 142°38'35″ = 0.65220000651 rad
∠ B' = β' = 136.95109202° = 136°57'3″ = 0.75113481825 rad
∠ C' = γ' = 80.40659317731° = 80°24'21″ = 1.7388244406 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.