# Triangle calculator

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

### Equilateral triangle.

Sides: a = 2.5   b = 2.5   c = 2.5

Area: T = 2.70663293868
Perimeter: p = 7.5
Semiperimeter: s = 3.75

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

Height: ha = 2.16550635095
Height: hb = 2.16550635095
Height: hc = 2.16550635095

Median: ma = 2.16550635095
Median: mb = 2.16550635095
Median: mc = 2.16550635095

Inradius: r = 0.72216878365
Circumradius: R = 1.4433375673

Vertex coordinates: A[2.5; 0] B[0; 0] C[1.25; 2.16550635095]
Centroid: CG[1.25; 0.72216878365]
Coordinates of the circumscribed circle: U[1.25; 0.72216878365]
Coordinates of the inscribed circle: I[1.25; 0.72216878365]

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. ### 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    