# 8 8 15 triangle

### Obtuse isosceles triangle.

Sides: a = 8   b = 8   c = 15

Area: T = 20.87991163606
Perimeter: p = 31
Semiperimeter: s = 15.5

Angle ∠ A = α = 20.36441348063° = 20°21'51″ = 0.35554212017 rad
Angle ∠ B = β = 20.36441348063° = 20°21'51″ = 0.35554212017 rad
Angle ∠ C = γ = 139.2721730387° = 139°16'18″ = 2.43107502502 rad

Height: ha = 5.22197790902
Height: hb = 5.22197790902
Height: hc = 2.78438821814

Median: ma = 11.33657840488
Median: mb = 11.33657840488
Median: mc = 2.78438821814

Inradius: r = 1.34770397652
Circumradius: R = 11.49547393297

Vertex coordinates: A[15; 0] B[0; 0] C[7.5; 2.78438821814]
Centroid: CG[7.5; 0.92879607271]
Coordinates of the circumscribed circle: U[7.5; -8.71108571483]
Coordinates of the inscribed circle: I[7.5; 1.34770397652]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 159.6365865194° = 159°38'9″ = 0.35554212017 rad
∠ B' = β' = 159.6365865194° = 159°38'9″ = 0.35554212017 rad
∠ C' = γ' = 40.72882696126° = 40°43'42″ = 2.43107502502 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.