# Triangle calculator SSS - result

Please enter the triangle sides:

### 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

Inradius: r = 2.59880762114
Circumradius: R = 10.60988111964

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?

### 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    