# 9 11 11 triangle

### Acute isosceles triangle.

Sides: a = 9   b = 11   c = 11

Area: T = 45.16884347747
Perimeter: p = 31
Semiperimeter: s = 15.5

Angle ∠ A = α = 48.2955479834° = 48°17'44″ = 0.84329151369 rad
Angle ∠ B = β = 65.8522260083° = 65°51'8″ = 1.14993387583 rad
Angle ∠ C = γ = 65.8522260083° = 65°51'8″ = 1.14993387583 rad

Height: ha = 10.03774299499
Height: hb = 8.21224426863
Height: hc = 8.21224426863

Median: ma = 10.03774299499
Median: mb = 8.41113019206
Median: mc = 8.41113019206

Inradius: r = 2.91440925661
Circumradius: R = 6.02774393248

Vertex coordinates: A[11; 0] B[0; 0] C[3.68218181818; 8.21224426863]
Centroid: CG[4.89439393939; 2.73774808954]
Coordinates of the circumscribed circle: U[5.5; 2.46657706329]
Coordinates of the inscribed circle: I[4.5; 2.91440925661]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 131.7054520166° = 131°42'16″ = 0.84329151369 rad
∠ B' = β' = 114.1487739917° = 114°8'52″ = 1.14993387583 rad
∠ C' = γ' = 114.1487739917° = 114°8'52″ = 1.14993387583 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.