# 3 9 11 triangle

### Obtuse scalene triangle.

Sides: a = 3   b = 9   c = 11

Area: T = 11.05438454847
Perimeter: p = 23
Semiperimeter: s = 11.5

Angle ∠ A = α = 12.90435205392° = 12°54'13″ = 0.22552089185 rad
Angle ∠ B = β = 42.06216646665° = 42°3'42″ = 0.73441145373 rad
Angle ∠ C = γ = 125.0354814794° = 125°2'5″ = 2.18222691978 rad

Height: ha = 7.36992303231
Height: hb = 2.45664101077
Height: hc = 2.01097900881

Median: ma = 9.93773034572
Median: mb = 6.69895440801
Median: mc = 3.84105728739

Inradius: r = 0.96112039552
Circumradius: R = 6.71771194045

Vertex coordinates: A[11; 0] B[0; 0] C[2.22772727273; 2.01097900881]
Centroid: CG[4.40990909091; 0.67699300294]
Coordinates of the circumscribed circle: U[5.5; -3.85661241026]
Coordinates of the inscribed circle: I[2.5; 0.96112039552]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.0966479461° = 167°5'47″ = 0.22552089185 rad
∠ B' = β' = 137.9388335334° = 137°56'18″ = 0.73441145373 rad
∠ C' = γ' = 54.96551852057° = 54°57'55″ = 2.18222691978 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.