# 10 21 28 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 21   c = 28

Area: T = 85.64113305595
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 16.93656240404° = 16°56'8″ = 0.29655824004 rad
Angle ∠ B = β = 37.71442488191° = 37°42'51″ = 0.65882378168 rad
Angle ∠ C = γ = 125.3550127141° = 125°21' = 2.18877724364 rad

Height: ha = 17.12882661119
Height: hb = 8.15663171961
Height: hc = 6.11772378971

Median: ma = 24.23883992871
Median: mb = 18.21440056001
Median: mc = 8.63113382508

Inradius: r = 2.90330959512
Circumradius: R = 17.16546095454

Vertex coordinates: A[28; 0] B[0; 0] C[7.91107142857; 6.11772378971]
Centroid: CG[11.97702380952; 2.0399079299]
Coordinates of the circumscribed circle: U[14; -9.93109526655]
Coordinates of the inscribed circle: I[8.5; 2.90330959512]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 163.064437596° = 163°3'52″ = 0.29655824004 rad
∠ B' = β' = 142.2865751181° = 142°17'9″ = 0.65882378168 rad
∠ C' = γ' = 54.65498728595° = 54°39' = 2.18877724364 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.