# 6 17 21 triangle

### Obtuse scalene triangle.

Sides: a = 6   b = 17   c = 21

Area: T = 41.95223539268
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 13.59332257052° = 13°35'36″ = 0.23772465445 rad
Angle ∠ B = β = 41.7522205202° = 41°45'8″ = 0.72987134507 rad
Angle ∠ C = γ = 124.6554569093° = 124°39'16″ = 2.17656326583 rad

Height: ha = 13.98441179756
Height: hb = 4.93655710502
Height: hc = 3.99554622787

Median: ma = 18.86879622641
Median: mb = 12.89437969582
Median: mc = 7.22884161474

Inradius: r = 1.90769251785
Circumradius: R = 12.76444804135

Vertex coordinates: A[21; 0] B[0; 0] C[4.47661904762; 3.99554622787]
Centroid: CG[8.49220634921; 1.33218207596]
Coordinates of the circumscribed circle: U[10.5; -7.25882339606]
Coordinates of the inscribed circle: I[5; 1.90769251785]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.4076774295° = 166°24'24″ = 0.23772465445 rad
∠ B' = β' = 138.2487794798° = 138°14'52″ = 0.72987134507 rad
∠ C' = γ' = 55.34554309073° = 55°20'44″ = 2.17656326583 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 ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.