Triangle calculator VC

Please enter the coordinates of the three vertices

Obtuse scalene triangle.

Sides: a = 9.48768329805   b = 3.60655512755   c = 12.04215945788

Area: T = 13.5
Perimeter: p = 25.13439788348
Semiperimeter: s = 12.56769894174

Angle ∠ A = α = 38.45437092167° = 38°27'13″ = 0.67111438354 rad
Angle ∠ B = β = 13.67113071322° = 13°40'17″ = 0.23986093225 rad
Angle ∠ C = γ = 127.8754983651° = 127°52'30″ = 2.23218394956 rad

Height: ha = 2.84660498942
Height: hb = 7.4888452649
Height: hc = 2.24222279561

Median: ma = 7.51766481892
Median: mb = 10.68987791632
Median: mc = 3.9055124838

Inradius: r = 1.07442429672
Circumradius: R = 7.62875167876

Vertex coordinates: A[1; -5] B[2; 7] C[-1; -2]
Centroid: CG[0.66766666667; 0]
Coordinates of the circumscribed circle: U[0; 0]
Coordinates of the inscribed circle: I[4.41663321983; 1.07442429672]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 141.5466290783° = 141°32'47″ = 0.67111438354 rad
∠ B' = β' = 166.3298692868° = 166°19'43″ = 0.23986093225 rad
∠ C' = γ' = 52.12550163489° = 52°7'30″ = 2.23218394956 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     