# 13 28 28 triangle

### Acute isosceles triangle.

Sides: a = 13   b = 28   c = 28

Area: T = 177.0288069808
Perimeter: p = 69
Semiperimeter: s = 34.5

Angle ∠ A = α = 26.84765272069° = 26°50'48″ = 0.46985602925 rad
Angle ∠ B = β = 76.57767363965° = 76°34'36″ = 1.33765161806 rad
Angle ∠ C = γ = 76.57767363965° = 76°34'36″ = 1.33765161806 rad

Height: ha = 27.23550876628
Height: hb = 12.64548621292
Height: hc = 12.64548621292

Median: ma = 27.23550876628
Median: mb = 16.74881342244
Median: mc = 16.74881342244

Inradius: r = 5.13112484002
Circumradius: R = 14.39331976593

Vertex coordinates: A[28; 0] B[0; 0] C[3.01878571429; 12.64548621292]
Centroid: CG[10.33992857143; 4.21549540431]
Coordinates of the circumscribed circle: U[14; 3.34112780281]
Coordinates of the inscribed circle: I[6.5; 5.13112484002]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 153.1533472793° = 153°9'12″ = 0.46985602925 rad
∠ B' = β' = 103.4233263603° = 103°25'24″ = 1.33765161806 rad
∠ C' = γ' = 103.4233263603° = 103°25'24″ = 1.33765161806 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.