Triangle calculator SSS - result

Please enter the triangle sides:

Obtuse scalene triangle.

Sides: a = 4   b = 20   c = 21

Area: T = 39.50987015732
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 10.84440625637° = 10°50'39″ = 0.1899264596 rad
Angle ∠ B = β = 70.16766380911° = 70°10' = 1.22546388597 rad
Angle ∠ C = γ = 98.98992993452° = 98°59'21″ = 1.72876891978 rad

Height: ha = 19.75443507866
Height: hb = 3.95108701573
Height: hc = 3.76327334832

Median: ma = 20.4088331632
Median: mb = 11.33657840488
Median: mc = 9.88768599666

Inradius: r = 1.75659422921
Circumradius: R = 10.63105695524

Vertex coordinates: A[21; 0] B[0; 0] C[1.35771428571; 3.76327334832]
Centroid: CG[7.45223809524; 1.25442444944]
Coordinates of the circumscribed circle: U[10.5; -1.66110264926]
Coordinates of the inscribed circle: I[2.5; 1.75659422921]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 169.1565937436° = 169°9'21″ = 0.1899264596 rad
∠ B' = β' = 109.8333361909° = 109°50' = 1.22546388597 rad
∠ C' = γ' = 81.01107006548° = 81°39″ = 1.72876891978 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    