# 13 14 20 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 14   c = 20

Area: T = 90.57883500623
Perimeter: p = 47
Semiperimeter: s = 23.5

Angle ∠ A = α = 40.31549091747° = 40°18'54″ = 0.70436279027 rad
Angle ∠ B = β = 44.16773564515° = 44°10'2″ = 0.7710865792 rad
Angle ∠ C = γ = 95.51877343738° = 95°31'4″ = 1.66770989589 rad

Height: ha = 13.93551307788
Height: hb = 12.94397642946
Height: hc = 9.05878350062

Median: ma = 15.99221855917
Median: mb = 15.34660092532
Median: mc = 9.08329510623

Inradius: r = 3.8544397875
Circumradius: R = 10.04765508521

Vertex coordinates: A[20; 0] B[0; 0] C[9.325; 9.05878350062]
Centroid: CG[9.775; 3.01992783354]
Coordinates of the circumscribed circle: U[10; -0.9666014505]
Coordinates of the inscribed circle: I[9.5; 3.8544397875]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 139.6855090825° = 139°41'6″ = 0.70436279027 rad
∠ B' = β' = 135.8332643548° = 135°49'58″ = 0.7710865792 rad
∠ C' = γ' = 84.48222656262° = 84°28'56″ = 1.66770989589 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    