# Equilateral triangle calculator

Please enter one property of the equilateral triangle

Use symbols: a, h, T, p, r, R

You have entered side a, b and c (as equilateral triangle).

### Equilateral triangle.

Sides: a = 1505   b = 1505   c = 1505

Area: T = 980784.5955103
Perimeter: p = 4515
Semiperimeter: s = 2257.5

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

Height: ha = 1303.36882327
Height: hb = 1303.36882327
Height: hc = 1303.36882327

Median: ma = 1303.36882327
Median: mb = 1303.36882327
Median: mc = 1303.36882327

Inradius: r = 434.4566077565
Circumradius: R = 868.912215513

Vertex coordinates: A[1505; 0] B[0; 0] C[752.5; 1303.36882327]
Centroid: CG[752.5; 434.4566077565]
Coordinates of the circumscribed circle: U[752.5; 434.4566077565]
Coordinates of the inscribed circle: I[752.5; 434.4566077565]

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. From we calculate b,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. ### 3. The triangle circumference is the sum of the lengths of its three sides ### 4. Semiperimeter of the triangle ### 5. The triangle area using Heron's formula ### 6. Calculate the heights of the triangle from its area. ### 7. Calculation of the inner angles of the triangle using a Law of Cosines    