# 5 26 26 triangle

### Acute isosceles triangle.

Sides: a = 5   b = 26   c = 26

Area: T = 64.6998821473
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 11.03554687476° = 11°2'8″ = 0.19326052641 rad
Angle ∠ B = β = 84.48222656262° = 84°28'56″ = 1.47444936947 rad
Angle ∠ C = γ = 84.48222656262° = 84°28'56″ = 1.47444936947 rad

Height: ha = 25.88795285892
Height: hb = 4.9776832421
Height: hc = 4.9776832421

Median: ma = 25.88795285892
Median: mb = 13.47221935853
Median: mc = 13.47221935853

Inradius: r = 2.27701340868
Circumradius: R = 13.06105161077

Vertex coordinates: A[26; 0] B[0; 0] C[0.48107692308; 4.9776832421]
Centroid: CG[8.82769230769; 1.65989441403]
Coordinates of the circumscribed circle: U[13; 1.25658188565]
Coordinates of the inscribed circle: I[2.5; 2.27701340868]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 168.9654531252° = 168°57'52″ = 0.19326052641 rad
∠ B' = β' = 95.51877343738° = 95°31'4″ = 1.47444936947 rad
∠ C' = γ' = 95.51877343738° = 95°31'4″ = 1.47444936947 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    