# 71 71 71 triangle

### Equilateral triangle.

Sides: a = 71   b = 71   c = 71

Area: T = 2182.817703024
Perimeter: p = 213
Semiperimeter: s = 106.5

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

Height: ha = 61.48878036687
Height: hb = 61.48878036687
Height: hc = 61.48878036687

Median: ma = 61.48878036687
Median: mb = 61.48878036687
Median: mc = 61.48878036687

Inradius: r = 20.49659345562
Circumradius: R = 40.99218691125

Vertex coordinates: A[71; 0] B[0; 0] C[35.5; 61.48878036687]
Centroid: CG[35.5; 20.49659345562]
Coordinates of the circumscribed circle: U[35.5; 20.49659345562]
Coordinates of the inscribed circle: I[35.5; 20.49659345562]

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    