6 21 21 triangle

Acute isosceles triangle.

Sides: a = 6   b = 21   c = 21

Area: T = 62.35438290725
Perimeter: p = 48
Semiperimeter: s = 24

Angle ∠ A = α = 16.42664214035° = 16°25'35″ = 0.28766951378 rad
Angle ∠ B = β = 81.78767892983° = 81°47'12″ = 1.42774487579 rad
Angle ∠ C = γ = 81.78767892983° = 81°47'12″ = 1.42774487579 rad

Height: ha = 20.78546096908
Height: hb = 5.93884599117
Height: hc = 5.93884599117

Median: ma = 20.78546096908
Median: mb = 11.32547516529
Median: mc = 11.32547516529

Vertex coordinates: A[21; 0] B[0; 0] C[0.85771428571; 5.93884599117]
Centroid: CG[7.28657142857; 1.97994866372]
Coordinates of the circumscribed circle: U[10.5; 1.51655444566]
Coordinates of the inscribed circle: I[3; 2.59880762114]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 163.5743578597° = 163°34'25″ = 0.28766951378 rad
∠ B' = β' = 98.21332107017° = 98°12'48″ = 1.42774487579 rad
∠ C' = γ' = 98.21332107017° = 98°12'48″ = 1.42774487579 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    