# 10 17 21 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 17   c = 21

Area: T = 84
Perimeter: p = 48
Semiperimeter: s = 24

Angle ∠ A = α = 28.07224869359° = 28°4'21″ = 0.49899573263 rad
Angle ∠ B = β = 53.13301023542° = 53°7'48″ = 0.9277295218 rad
Angle ∠ C = γ = 98.797741071° = 98°47'51″ = 1.72443401093 rad

Height: ha = 16.8
Height: hb = 9.88223529412
Height: hc = 8

Median: ma = 18.43990889146
Median: mb = 14.08801278403
Median: mc = 9.17987798753

Inradius: r = 3.5
Circumradius: R = 10.625

Vertex coordinates: A[21; 0] B[0; 0] C[6; 8]
Centroid: CG[9; 2.66766666667]
Coordinates of the circumscribed circle: U[10.5; -1.625]
Coordinates of the inscribed circle: I[7; 3.5]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.9287513064° = 151°55'39″ = 0.49899573263 rad
∠ B' = β' = 126.8769897646° = 126°52'12″ = 0.9277295218 rad
∠ C' = γ' = 81.203258929° = 81°12'9″ = 1.72443401093 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.