# 12 28 28 triangle

### Acute isosceles triangle.

Sides: a = 12   b = 28   c = 28

Area: T = 164.0987531974
Perimeter: p = 68
Semiperimeter: s = 34

Angle ∠ A = α = 24.74772502324° = 24°44'50″ = 0.43219209974 rad
Angle ∠ B = β = 77.62663748838° = 77°37'35″ = 1.35548358281 rad
Angle ∠ C = γ = 77.62663748838° = 77°37'35″ = 1.35548358281 rad

Height: ha = 27.35495886624
Height: hb = 11.72112522839
Height: hc = 11.72112522839

Median: ma = 27.35495886624
Median: mb = 16.37107055437
Median: mc = 16.37107055437

Inradius: r = 4.82663979992
Circumradius: R = 14.33329395129

Vertex coordinates: A[28; 0] B[0; 0] C[2.57114285714; 11.72112522839]
Centroid: CG[10.19904761905; 3.90770840946]
Coordinates of the circumscribed circle: U[14; 3.07113441813]
Coordinates of the inscribed circle: I[6; 4.82663979992]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 155.2532749768° = 155°15'10″ = 0.43219209974 rad
∠ B' = β' = 102.3743625116° = 102°22'25″ = 1.35548358281 rad
∠ C' = γ' = 102.3743625116° = 102°22'25″ = 1.35548358281 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.