# 9 11 13 triangle

### Acute scalene triangle.

Sides: a = 9   b = 11   c = 13

Area: T = 48.80876582106
Perimeter: p = 33
Semiperimeter: s = 16.5

Angle ∠ A = α = 43.04990798002° = 43°2'57″ = 0.75113481825 rad
Angle ∠ B = β = 56.54549884266° = 56°32'42″ = 0.98768962235 rad
Angle ∠ C = γ = 80.40659317731° = 80°24'21″ = 1.40333482476 rad

Height: ha = 10.8466146269
Height: hb = 8.87441196746
Height: hc = 7.50988704939

Median: ma = 11.16991539518
Median: mb = 9.7343961167
Median: mc = 7.66548548584

Inradius: r = 2.95880398915
Circumradius: R = 6.59222031869

Vertex coordinates: A[13; 0] B[0; 0] C[4.96215384615; 7.50988704939]
Centroid: CG[5.98771794872; 2.50329568313]
Coordinates of the circumscribed circle: U[6.5; 1.09987005311]
Coordinates of the inscribed circle: I[5.5; 2.95880398915]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 136.95109202° = 136°57'3″ = 0.75113481825 rad
∠ B' = β' = 123.4555011573° = 123°27'18″ = 0.98768962235 rad
∠ C' = γ' = 99.59440682269° = 99°35'39″ = 1.40333482476 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.