# 10 26 26 triangle

### Acute isosceles triangle.

Sides: a = 10   b = 26   c = 26

Area: T = 127.5743508222
Perimeter: p = 62
Semiperimeter: s = 31

Angle ∠ A = α = 22.17549784219° = 22°10'30″ = 0.3877026385 rad
Angle ∠ B = β = 78.9132510789° = 78°54'45″ = 1.37772831343 rad
Angle ∠ C = γ = 78.9132510789° = 78°54'45″ = 1.37772831343 rad

Height: ha = 25.51547016443
Height: hb = 9.81333467863
Height: hc = 9.81333467863

Median: ma = 25.51547016443
Median: mb = 14.79986485869
Median: mc = 14.79986485869

Inradius: r = 4.11552744588
Circumradius: R = 13.24772644482

Vertex coordinates: A[26; 0] B[0; 0] C[1.92330769231; 9.81333467863]
Centroid: CG[9.30876923077; 3.27111155954]
Coordinates of the circumscribed circle: U[13; 2.54875508554]
Coordinates of the inscribed circle: I[5; 4.11552744588]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.8255021578° = 157°49'30″ = 0.3877026385 rad
∠ B' = β' = 101.0877489211° = 101°5'15″ = 1.37772831343 rad
∠ C' = γ' = 101.0877489211° = 101°5'15″ = 1.37772831343 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    