# 4 16 17 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 16   c = 17

Area: T = 31.71765177786
Perimeter: p = 37
Semiperimeter: s = 18.5

Angle ∠ A = α = 13.48661135663° = 13°29'10″ = 0.2355377085 rad
Angle ∠ B = β = 68.88217401101° = 68°52'54″ = 1.20222131594 rad
Angle ∠ C = γ = 97.63221463237° = 97°37'56″ = 1.70440024091 rad

Height: ha = 15.85882588893
Height: hb = 3.96545647223
Height: hc = 3.73113550328

Median: ma = 16.38659696082
Median: mb = 9.40774438611
Median: mc = 7.98443597113

Inradius: r = 1.71444063664
Circumradius: R = 8.57659729961

Vertex coordinates: A[17; 0] B[0; 0] C[1.44111764706; 3.73113550328]
Centroid: CG[6.14770588235; 1.24437850109]
Coordinates of the circumscribed circle: U[8.5; -1.13989964135]
Coordinates of the inscribed circle: I[2.5; 1.71444063664]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.5143886434° = 166°30'50″ = 0.2355377085 rad
∠ B' = β' = 111.118825989° = 111°7'6″ = 1.20222131594 rad
∠ C' = γ' = 82.36878536763° = 82°22'4″ = 1.70440024091 rad

# How did we calculate this triangle?

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. ### 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    