# 1 4 4 triangle

### Acute isosceles triangle.

Sides: a = 1   b = 4   c = 4

Area: T = 1.98443134833
Perimeter: p = 9
Semiperimeter: s = 4.5

Angle ∠ A = α = 14.36215115629° = 14°21'41″ = 0.25106556623 rad
Angle ∠ B = β = 82.81992442185° = 82°49'9″ = 1.44554684956 rad
Angle ∠ C = γ = 82.81992442185° = 82°49'9″ = 1.44554684956 rad

Height: ha = 3.96986269666
Height: hb = 0.99221567416
Height: hc = 0.99221567416

Median: ma = 3.96986269666
Median: mb = 2.12113203436
Median: mc = 2.12113203436

Inradius: r = 0.44109585518
Circumradius: R = 2.01658105227

Vertex coordinates: A[4; 0] B[0; 0] C[0.125; 0.99221567416]
Centroid: CG[1.375; 0.33107189139]
Coordinates of the circumscribed circle: U[2; 0.25219763153]
Coordinates of the inscribed circle: I[0.5; 0.44109585518]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 165.6388488437° = 165°38'19″ = 0.25106556623 rad
∠ B' = β' = 97.18107557815° = 97°10'51″ = 1.44554684956 rad
∠ C' = γ' = 97.18107557815° = 97°10'51″ = 1.44554684956 rad

# How did we calculate this triangle?

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. ### 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    