Triangle calculator VC

Please enter the coordinates of the three vertices

Obtuse scalene triangle.

Sides: a = 18.38547763109   b = 7.21111025509   c = 11.4021754251

Area: T = 13
Perimeter: p = 36.99876331128
Semiperimeter: s = 18.49988165564

Angle ∠ A = α = 161.5655051177° = 161°33'54″ = 2.82198420992 rad
Angle ∠ B = β = 7.12550163489° = 7°7'30″ = 0.12443549945 rad
Angle ∠ C = γ = 11.3109932474° = 11°18'36″ = 0.19773955598 rad

Height: ha = 1.41442135624
Height: hb = 3.60655512755
Height: hc = 2.28803508502

Median: ma = 2.55495097568
Median: mb = 14.86660687473
Median: mc = 12.7487548784

Inradius: r = 0.70327476574
Circumradius: R = 29.06988837075

Vertex coordinates: A[-2; -5] B[-9; 4] C[4; -9]
Centroid: CG[-2.33333333333; -3.33333333333]
Coordinates of the circumscribed circle: U[0; 0]
Coordinates of the inscribed circle: I[5.62219812593; 0.70327476574]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 18.43549488229° = 18°26'6″ = 2.82198420992 rad
∠ B' = β' = 172.8754983651° = 172°52'30″ = 0.12443549945 rad
∠ C' = γ' = 168.6990067526° = 168°41'24″ = 0.19773955598 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     