# 1 11 11 triangle

### Acute isosceles triangle.

Sides: a = 1   b = 11   c = 11

Area: T = 5.4944315244
Perimeter: p = 23
Semiperimeter: s = 11.5

Angle ∠ A = α = 5.21105025301° = 5°12'38″ = 0.09109404248 rad
Angle ∠ B = β = 87.39547487349° = 87°23'41″ = 1.52553261144 rad
Angle ∠ C = γ = 87.39547487349° = 87°23'41″ = 1.52553261144 rad

Height: ha = 10.98986304879
Height: hb = 0.9998966408
Height: hc = 0.9998966408

Median: ma = 10.98986304879
Median: mb = 5.54552682532
Median: mc = 5.54552682532

Inradius: r = 0.4787766543
Circumradius: R = 5.50656906378

Vertex coordinates: A[11; 0] B[0; 0] C[0.04554545455; 0.9998966408]
Centroid: CG[3.68218181818; 0.33329888027]
Coordinates of the circumscribed circle: U[5.5; 0.25502586654]
Coordinates of the inscribed circle: I[0.5; 0.4787766543]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 174.789949747° = 174°47'22″ = 0.09109404248 rad
∠ B' = β' = 92.60552512651° = 92°36'19″ = 1.52553261144 rad
∠ C' = γ' = 92.60552512651° = 92°36'19″ = 1.52553261144 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    