# 20 25 26 triangle

### Acute scalene triangle.

Sides: a = 20   b = 25   c = 26

Area: T = 234.2810681022
Perimeter: p = 71
Semiperimeter: s = 35.5

Angle ∠ A = α = 46.1265829757° = 46°7'33″ = 0.80550475995 rad
Angle ∠ B = β = 64.330033309° = 64°18'1″ = 1.12222525225 rad
Angle ∠ C = γ = 69.5743837153° = 69°34'26″ = 1.21442925316 rad

Height: ha = 23.42880681022
Height: hb = 18.74224544817
Height: hc = 18.02215908478

Median: ma = 23.46327364133
Median: mb = 19.53884236826
Median: mc = 18.53437529929

Inradius: r = 6.59994558034
Circumradius: R = 13.87222492432

Vertex coordinates: A[26; 0] B[0; 0] C[8.67330769231; 18.02215908478]
Centroid: CG[11.55876923077; 6.00771969493]
Coordinates of the circumscribed circle: U[13; 4.84114149859]
Coordinates of the inscribed circle: I[10.5; 6.59994558034]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.8744170243° = 133°52'27″ = 0.80550475995 rad
∠ B' = β' = 115.769966691° = 115°41'59″ = 1.12222525225 rad
∠ C' = γ' = 110.4266162847° = 110°25'34″ = 1.21442925316 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    