# 9 16 20 triangle

### Obtuse scalene triangle.

Sides: a = 9   b = 16   c = 20

Area: T = 70.2566227482
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 26.04765623605° = 26°2'48″ = 0.4554598272 rad
Angle ∠ B = β = 51.31878125465° = 51°19'4″ = 0.89656647939 rad
Angle ∠ C = γ = 102.6365625093° = 102°38'8″ = 1.79113295877 rad

Height: ha = 15.6122494996
Height: hb = 8.78220284352
Height: hc = 7.02656227482

Median: ma = 17.54328047928
Median: mb = 13.28553302556
Median: mc = 8.27664726786

Inradius: r = 3.12224989992
Circumradius: R = 10.24882018435

Vertex coordinates: A[20; 0] B[0; 0] C[5.625; 7.02656227482]
Centroid: CG[8.54216666667; 2.34218742494]
Coordinates of the circumscribed circle: U[10; -2.24217941533]
Coordinates of the inscribed circle: I[6.5; 3.12224989992]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 153.953343764° = 153°57'12″ = 0.4554598272 rad
∠ B' = β' = 128.6822187453° = 128°40'56″ = 0.89656647939 rad
∠ C' = γ' = 77.3644374907° = 77°21'52″ = 1.79113295877 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.