# 10 16 21 triangle

### Obtuse scalene triangle.

Sides: a = 10   b = 16   c = 21

Area: T = 77.12661142545
Perimeter: p = 47
Semiperimeter: s = 23.5

Angle ∠ A = α = 27.32880163439° = 27°19'41″ = 0.47769638632 rad
Angle ∠ B = β = 47.26878899574° = 47°16'4″ = 0.82549803102 rad
Angle ∠ C = γ = 105.4044093699° = 105°24'15″ = 1.84396484801 rad

Height: ha = 15.42552228509
Height: hb = 9.64107642818
Height: hc = 7.34553442147

Median: ma = 17.98661057486
Median: mb = 14.37701078632
Median: mc = 8.23110388166

Inradius: r = 3.28219623087
Circumradius: R = 10.89112526985

Vertex coordinates: A[21; 0] B[0; 0] C[6.78657142857; 7.34553442147]
Centroid: CG[9.26219047619; 2.44884480716]
Coordinates of the circumscribed circle: U[10.5; -2.8932988998]
Coordinates of the inscribed circle: I[7.5; 3.28219623087]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 152.6721983656° = 152°40'19″ = 0.47769638632 rad
∠ B' = β' = 132.7322110043° = 132°43'56″ = 0.82549803102 rad
∠ C' = γ' = 74.59659063013° = 74°35'45″ = 1.84396484801 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.