Triangle calculator VC

Please enter the coordinates of the three vertices

Acute scalene triangle.

Sides: a = 17.26326765016   b = 18.43990889146   c = 9.48768329805

Area: T = 81
Perimeter: p = 45.18985983967
Semiperimeter: s = 22.59442991984

Angle ∠ A = α = 67.83436541779° = 67°50'1″ = 1.18439206091 rad
Angle ∠ B = β = 81.57330309785° = 81°34'23″ = 1.42437179714 rad
Angle ∠ C = γ = 30.59333148436° = 30°35'36″ = 0.53439540731 rad

Height: ha = 9.38444080311
Height: hb = 8.78656835417
Height: hc = 17.07662993649

Median: ma = 11.85332695911
Median: mb = 10.44403065089
Median: mc = 17.21991753577

Inradius: r = 3.58549750988
Circumradius: R = 9.32201700238

Vertex coordinates: A[4; -5] B[-5; -8] C[-8; 9]
Centroid: CG[-3; -1.33333333333]
Coordinates of the circumscribed circle: U[0; 0]
Coordinates of the inscribed circle: I[0.5311107422; 3.58549750988]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 112.1666345822° = 112°9'59″ = 1.18439206091 rad
∠ B' = β' = 98.42769690215° = 98°25'37″ = 1.42437179714 rad
∠ C' = γ' = 149.4076685156° = 149°24'24″ = 0.53439540731 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     