# 11 17 21 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 17   c = 21

Area: T = 93.17882565838
Perimeter: p = 49
Semiperimeter: s = 24.5

Angle ∠ A = α = 31.46769762933° = 31°28'1″ = 0.5499202342 rad
Angle ∠ B = β = 53.77884533802° = 53°46'42″ = 0.93986110781 rad
Angle ∠ C = γ = 94.75545703266° = 94°45'16″ = 1.65437792335 rad

Height: ha = 16.94215011971
Height: hb = 10.96221478334
Height: hc = 8.87441196746

Median: ma = 18.29661744635
Median: mb = 14.44881832768
Median: mc = 9.7343961167

Inradius: r = 3.80331941463
Circumradius: R = 10.53662563756

Vertex coordinates: A[21; 0] B[0; 0] C[6.5; 8.87441196746]
Centroid: CG[9.16766666667; 2.95880398915]
Coordinates of the circumscribed circle: U[10.5; -0.87333260632]
Coordinates of the inscribed circle: I[7.5; 3.80331941463]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.5333023707° = 148°31'59″ = 0.5499202342 rad
∠ B' = β' = 126.222154662° = 126°13'18″ = 0.93986110781 rad
∠ C' = γ' = 85.24554296734° = 85°14'44″ = 1.65437792335 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.