Triangle calculator VC

Please enter the coordinates of the three vertices

Obtuse isosceles triangle.

Sides: a = 12.72879220614   b = 6.70882039325   c = 6.70882039325

Area: T = 13.5
Perimeter: p = 26.14443299264
Semiperimeter: s = 13.07221649632

Angle ∠ A = α = 143.1330102354° = 143°7'48″ = 2.49880915448 rad
Angle ∠ B = β = 18.43549488229° = 18°26'6″ = 0.32217505544 rad
Angle ∠ C = γ = 18.43549488229° = 18°26'6″ = 0.32217505544 rad

Height: ha = 2.12113203436
Height: hb = 4.02549223595
Height: hc = 4.02549223595

Median: ma = 2.12113203436
Median: mb = 9.60546863561
Median: mc = 9.60546863561

Inradius: r = 1.03327287055
Circumradius: R = 10.60766017178

Vertex coordinates: A[-2; -1] B[1; 5] C[-8; -4]
Centroid: CG[-3; 0]
Coordinates of the circumscribed circle: U[0; 0]
Coordinates of the inscribed circle: I[3.09881861164; 1.03327287055]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 36.87698976458° = 36°52'12″ = 2.49880915448 rad
∠ B' = β' = 161.5655051177° = 161°33'54″ = 0.32217505544 rad
∠ C' = γ' = 161.5655051177° = 161°33'54″ = 0.32217505544 rad

How did we calculate this triangle?

1. We compute side a from coordinates using the Pythagorean theorem 2. We compute side b from coordinates using the Pythagorean theorem 3. We compute side c from coordinates using the Pythagorean theorem 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. 4. The triangle circumference is the sum of the lengths of its three sides 5. Semiperimeter of the triangle 6. The triangle area using Heron's formula 7. Calculate the heights of the triangle from its area. 8. Calculation of the inner angles of the triangle using a Law of Cosines     