# 16 20 21 triangle

### Acute scalene triangle.

Sides: a = 16   b = 20   c = 21

Area: T = 150.7011484731
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 45.85988345181° = 45°51'32″ = 0.88003876535 rad
Angle ∠ B = β = 63.77107223958° = 63°46'15″ = 1.11330090722 rad
Angle ∠ C = γ = 70.37704430861° = 70°22'14″ = 1.22881959279 rad

Height: ha = 18.83876855913
Height: hb = 15.07701484731
Height: hc = 14.35325223553

Median: ma = 18.88112075885
Median: mb = 15.76438827704
Median: mc = 14.75663545634

Inradius: r = 5.28877713941
Circumradius: R = 11.14878662802

Vertex coordinates: A[21; 0] B[0; 0] C[7.07114285714; 14.35325223553]
Centroid: CG[9.35771428571; 4.78441741184]
Coordinates of the circumscribed circle: U[10.5; 3.74549863285]
Coordinates of the inscribed circle: I[8.5; 5.28877713941]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 134.1411165482° = 134°8'28″ = 0.88003876535 rad
∠ B' = β' = 116.2299277604° = 116°13'45″ = 1.11330090722 rad
∠ C' = γ' = 109.6329556914° = 109°37'46″ = 1.22881959279 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.