# 5.5 5.5 5.5 triangle

### Equilateral triangle.

Sides: a = 5.5   b = 5.5   c = 5.5

Area: T = 13.09986342322
Perimeter: p = 16.5
Semiperimeter: s = 8.25

Angle ∠ A = α = 60° = 1.04771975512 rad
Angle ∠ B = β = 60° = 1.04771975512 rad
Angle ∠ C = γ = 60° = 1.04771975512 rad

Height: ha = 4.76331397208
Height: hb = 4.76331397208
Height: hc = 4.76331397208

Median: ma = 4.76331397208
Median: mb = 4.76331397208
Median: mc = 4.76331397208

Inradius: r = 1.58877132403
Circumradius: R = 3.17554264805

Vertex coordinates: A[5.5; 0] B[0; 0] C[2.75; 4.76331397208]
Centroid: CG[2.75; 1.58877132403]
Coordinates of the circumscribed circle: U[2.75; 1.58877132403]
Coordinates of the inscribed circle: I[2.75; 1.58877132403]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 120° = 1.04771975512 rad
∠ B' = β' = 120° = 1.04771975512 rad
∠ C' = γ' = 120° = 1.04771975512 rad

# How did we calculate this triangle?

### 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    