# 19 21 26 triangle

### Acute scalene triangle.

Sides: a = 19   b = 21   c = 26

Area: T = 196.9977461913
Perimeter: p = 66
Semiperimeter: s = 33

Angle ∠ A = α = 46.18769385396° = 46°11'13″ = 0.80661141489 rad
Angle ∠ B = β = 52.89877817478° = 52°53'52″ = 0.92332404585 rad
Angle ∠ C = γ = 80.91552797126° = 80°54'55″ = 1.41222380462 rad

Height: ha = 20.73765749382
Height: hb = 18.76216630393
Height: hc = 15.15436509164

Median: ma = 21.63990850084
Median: mb = 20.20551973512
Median: mc = 15.23215462117

Inradius: r = 5.9769620058
Circumradius: R = 13.1655144235

Vertex coordinates: A[26; 0] B[0; 0] C[11.46215384615; 15.15436509164]
Centroid: CG[12.48771794872; 5.05112169721]
Coordinates of the circumscribed circle: U[13; 2.07987069845]
Coordinates of the inscribed circle: I[12; 5.9769620058]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.813306146° = 133°48'47″ = 0.80661141489 rad
∠ B' = β' = 127.1022218252° = 127°6'8″ = 0.92332404585 rad
∠ C' = γ' = 99.08547202874° = 99°5'5″ = 1.41222380462 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    