# 19 20 26 triangle

### Acute scalene triangle.

Sides: a = 19   b = 20   c = 26

Area: T = 188.8087938128
Perimeter: p = 65
Semiperimeter: s = 32.5

Angle ∠ A = α = 46.56774634422° = 46°34'3″ = 0.81327555614 rad
Angle ∠ B = β = 49.85440523379° = 49°51'15″ = 0.87701173588 rad
Angle ∠ C = γ = 83.57884842199° = 83°34'43″ = 1.45987197335 rad

Height: ha = 19.87545198029
Height: hb = 18.88107938128
Height: hc = 14.52436875483

Median: ma = 21.16601039695
Median: mb = 20.45772725455
Median: mc = 14.54330395722

Inradius: r = 5.80994750193
Circumradius: R = 13.08220770805

Vertex coordinates: A[26; 0] B[0; 0] C[12.25; 14.52436875483]
Centroid: CG[12.75; 4.84112291828]
Coordinates of the circumscribed circle: U[13; 1.46331270419]
Coordinates of the inscribed circle: I[12.5; 5.80994750193]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.4332536558° = 133°25'57″ = 0.81327555614 rad
∠ B' = β' = 130.1465947662° = 130°8'45″ = 0.87701173588 rad
∠ C' = γ' = 96.42215157801° = 96°25'17″ = 1.45987197335 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    