# 11 13 13 triangle

### Acute isosceles triangle.

Sides: a = 11   b = 13   c = 13

Area: T = 64.78657044416
Perimeter: p = 37
Semiperimeter: s = 18.5

Angle ∠ A = α = 50.05879989752° = 50°3'29″ = 0.87436768991 rad
Angle ∠ B = β = 64.97110005124° = 64°58'16″ = 1.13439578773 rad
Angle ∠ C = γ = 64.97110005124° = 64°58'16″ = 1.13439578773 rad

Height: ha = 11.77992189894
Height: hb = 9.96770314526
Height: hc = 9.96770314526

Median: ma = 11.77992189894
Median: mb = 10.13765674664
Median: mc = 10.13765674664

Inradius: r = 3.50219299698
Circumradius: R = 7.17436504836

Vertex coordinates: A[13; 0] B[0; 0] C[4.65438461538; 9.96770314526]
Centroid: CG[5.88546153846; 3.32223438175]
Coordinates of the circumscribed circle: U[6.5; 3.03550059738]
Coordinates of the inscribed circle: I[5.5; 3.50219299698]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 129.9422001025° = 129°56'31″ = 0.87436768991 rad
∠ B' = β' = 115.0298999488° = 115°1'44″ = 1.13439578773 rad
∠ C' = γ' = 115.0298999488° = 115°1'44″ = 1.13439578773 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.