# 8 13 13 triangle

### Acute isosceles triangle.

Sides: a = 8   b = 13   c = 13

Area: T = 49.47772675074
Perimeter: p = 34
Semiperimeter: s = 17

Angle ∠ A = α = 35.84404262788° = 35°50'26″ = 0.62655334439 rad
Angle ∠ B = β = 72.08797868606° = 72°4'47″ = 1.25880296049 rad
Angle ∠ C = γ = 72.08797868606° = 72°4'47″ = 1.25880296049 rad

Height: ha = 12.36993168769
Height: hb = 7.61218873088
Height: hc = 7.61218873088

Median: ma = 12.36993168769
Median: mb = 8.61768439698
Median: mc = 8.61768439698

Inradius: r = 2.91104275004
Circumradius: R = 6.83114201052

Vertex coordinates: A[13; 0] B[0; 0] C[2.46215384615; 7.61218873088]
Centroid: CG[5.15438461538; 2.53772957696]
Coordinates of the circumscribed circle: U[6.5; 2.1021975417]
Coordinates of the inscribed circle: I[4; 2.91104275004]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 144.1659573721° = 144°9'34″ = 0.62655334439 rad
∠ B' = β' = 107.9220213139° = 107°55'13″ = 1.25880296049 rad
∠ C' = γ' = 107.9220213139° = 107°55'13″ = 1.25880296049 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.