# 5 5 9 triangle

### Obtuse isosceles triangle.

Sides: a = 5   b = 5   c = 9

Area: T = 9.8087522623
Perimeter: p = 19
Semiperimeter: s = 9.5

Angle ∠ A = α = 25.84219327632° = 25°50'31″ = 0.45110268118 rad
Angle ∠ B = β = 25.84219327632° = 25°50'31″ = 0.45110268118 rad
Angle ∠ C = γ = 128.3166134474° = 128°18'58″ = 2.243953903 rad

Height: ha = 3.92330090492
Height: hb = 3.92330090492
Height: hc = 2.17994494718

Median: ma = 6.83773971656
Median: mb = 6.83773971656
Median: mc = 2.17994494718

Inradius: r = 1.03223708024
Circumradius: R = 5.73553933468

Vertex coordinates: A[9; 0] B[0; 0] C[4.5; 2.17994494718]
Centroid: CG[4.5; 0.72664831573]
Coordinates of the circumscribed circle: U[4.5; -3.5565943875]
Coordinates of the inscribed circle: I[4.5; 1.03223708024]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 154.1588067237° = 154°9'29″ = 0.45110268118 rad
∠ B' = β' = 154.1588067237° = 154°9'29″ = 0.45110268118 rad
∠ C' = γ' = 51.68438655263° = 51°41'2″ = 2.243953903 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.