# 11 11 20 triangle

### Obtuse isosceles triangle.

Sides: a = 11   b = 11   c = 20

Area: T = 45.82657569496
Perimeter: p = 42
Semiperimeter: s = 21

Angle ∠ A = α = 24.62199773287° = 24°37'12″ = 0.43296996662 rad
Angle ∠ B = β = 24.62199773287° = 24°37'12″ = 0.43296996662 rad
Angle ∠ C = γ = 130.7660045343° = 130°45'36″ = 2.28221933213 rad

Height: ha = 8.3321955809
Height: hb = 8.3321955809
Height: hc = 4.5832575695

Median: ma = 15.17439909055
Median: mb = 15.17439909055
Median: mc = 4.5832575695

Inradius: r = 2.18221789024
Circumradius: R = 13.20221823593

Vertex coordinates: A[20; 0] B[0; 0] C[10; 4.5832575695]
Centroid: CG[10; 1.52875252317]
Coordinates of the circumscribed circle: U[10; -8.62196066643]
Coordinates of the inscribed circle: I[10; 2.18221789024]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 155.3880022671° = 155°22'48″ = 0.43296996662 rad
∠ B' = β' = 155.3880022671° = 155°22'48″ = 0.43296996662 rad
∠ C' = γ' = 49.24399546573° = 49°14'24″ = 2.28221933213 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 ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.