# 4 8 9 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 8   c = 9

Area: T = 15.99880467558
Perimeter: p = 21
Semiperimeter: s = 10.5

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 = 7.99990233779
Height: hb = 43.9995116889
Height: hc = 3.55551215013

Median: ma = 8.27664726786
Median: mb = 5.70108771255
Median: mc = 4.44440972087

Inradius: r = 1.52436235006
Circumradius: R = 4.5010549417

Vertex coordinates: A[9; 0] B[0; 0] C[1.83333333333; 3.55551215013]
Centroid: CG[3.61111111111; 1.18550405004]
Coordinates of the circumscribed circle: U[4.5; -0.07703210846]
Coordinates of the inscribed circle: I[2.5; 1.52436235006]

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.