# Triangle calculator

You have entered side a, b and c.

### Equilateral triangle.

Sides: a = 80   b = 80   c = 80

Area: T = 2771.281129211
Perimeter: p = 240
Semiperimeter: s = 120

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

Height: ha = 69.28220323028
Height: hb = 69.28220323028
Height: hc = 69.28220323028

Median: ma = 69.28220323028
Median: mb = 69.28220323028
Median: mc = 69.28220323028

Vertex coordinates: A[80; 0] B[0; 0] C[40; 69.28220323028]
Centroid: CG[40; 23.09440107676]
Coordinates of the circumscribed circle: U[40; 23.09440107676]
Coordinates of the inscribed circle: I[40; 23.09440107676]

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. 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. ### 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    