7 17 21 triangle
Obtuse scalene triangle.
Sides: a = 7 b = 17 c = 21Area: T = 53.63994211378
Perimeter: p = 45
Semiperimeter: s = 22.5
Angle ∠ A = α = 17.48876943436° = 17°29'16″ = 0.30552178449 rad
Angle ∠ B = β = 46.86986278687° = 46°52'7″ = 0.81880118722 rad
Angle ∠ C = γ = 115.6443677788° = 115°38'37″ = 2.01883629365 rad
Height: ha = 15.32655488965
Height: hb = 6.31105201339
Height: hc = 5.10985162988
Median: ma = 18.7821639971
Median: mb = 13.14334394281
Median: mc = 7.66548548584
Inradius: r = 2.38439742728
Circumradius: R = 11.64772174149
Vertex coordinates: A[21; 0] B[0; 0] C[4.78657142857; 5.10985162988]
Centroid: CG[8.59552380952; 1.70328387663]
Coordinates of the circumscribed circle: U[10.5; -5.04106024947]
Coordinates of the inscribed circle: I[5.5; 2.38439742728]
Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 162.5122305656° = 162°30'44″ = 0.30552178449 rad
∠ B' = β' = 133.1311372131° = 133°7'53″ = 0.81880118722 rad
∠ C' = γ' = 64.35663222123° = 64°21'23″ = 2.01883629365 rad
Calculate another triangle
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

6. Inradius

7. Circumradius
