19 21 21 triangle
Acute isosceles triangle.
Sides: a = 19 b = 21 c = 21Area: T = 177.9199047603
Perimeter: p = 61
Semiperimeter: s = 30.5
Angle ∠ A = α = 53.79330926066° = 53°47'35″ = 0.93988665808 rad
Angle ∠ B = β = 63.10334536967° = 63°6'12″ = 1.10113630364 rad
Angle ∠ C = γ = 63.10334536967° = 63°6'12″ = 1.10113630364 rad
Height: ha = 18.72883208003
Height: hb = 16.94546712003
Height: hc = 16.94546712003
Median: ma = 18.72883208003
Median: mb = 17.0511392905
Median: mc = 17.0511392905
Inradius: r = 5.83334113968
Circumradius: R = 11.77436129336
Vertex coordinates: A[21; 0] B[0; 0] C[8.59552380952; 16.94546712003]
Centroid: CG[9.86550793651; 5.64882237334]
Coordinates of the circumscribed circle: U[10.5; 5.32661582319]
Coordinates of the inscribed circle: I[9.5; 5.83334113968]
Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 126.2076907393° = 126°12'25″ = 0.93988665808 rad
∠ B' = β' = 116.8976546303° = 116°53'48″ = 1.10113630364 rad
∠ C' = γ' = 116.8976546303° = 116°53'48″ = 1.10113630364 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
