# Triangle calculator

Please enter what you know about the triangle:
You have entered side a, b and c (as equilateral triangle).

### Equilateral triangle.

Sides: a = 90   b = 90   c = 90

Area: T = 3507.403288533
Perimeter: p = 270
Semiperimeter: s = 135

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

Height: ha = 77.94222863406
Height: hb = 77.94222863406
Height: hc = 77.94222863406

Median: ma = 77.94222863406
Median: mb = 77.94222863406
Median: mc = 77.94222863406

Inradius: r = 25.98107621135
Circumradius: R = 51.96215242271

Vertex coordinates: A[90; 0] B[0; 0] C[45; 77.94222863406]
Centroid: CG[45; 25.98107621135]
Coordinates of the circumscribed circle: U[45; 25.98107621135]
Coordinates of the inscribed circle: I[45; 25.98107621135]

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. Input data entered: side a, b and c (as equilateral triangle). ### 2. The triangle circumference is the sum of the lengths of its three sides ### 3. Semiperimeter of the triangle ### 4. The triangle area using Heron's formula ### 5. Calculate the heights of the triangle from its area. ### 6. Calculation of the inner angles of the triangle using a Law of Cosines    