# 6 9 12 triangle

### Obtuse scalene triangle.

Sides: a = 6   b = 9   c = 12

Area: T = 26.14326375869
Perimeter: p = 27
Semiperimeter: s = 13.5

Angle ∠ A = α = 28.95550243719° = 28°57'18″ = 0.50553605103 rad
Angle ∠ B = β = 46.56774634422° = 46°34'3″ = 0.81327555614 rad
Angle ∠ C = γ = 104.4787512186° = 104°28'39″ = 1.82334765819 rad

Height: ha = 8.7144212529
Height: hb = 5.80994750193
Height: hc = 4.35771062645

Median: ma = 10.17334949747
Median: mb = 8.35216465442
Median: mc = 4.74334164903

Inradius: r = 1.93664916731
Circumradius: R = 6.19767733539

Vertex coordinates: A[12; 0] B[0; 0] C[4.125; 4.35771062645]
Centroid: CG[5.375; 1.45223687548]
Coordinates of the circumscribed circle: U[6; -1.54991933385]
Coordinates of the inscribed circle: I[4.5; 1.93664916731]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.0454975628° = 151°2'42″ = 0.50553605103 rad
∠ B' = β' = 133.4332536558° = 133°25'57″ = 0.81327555614 rad
∠ C' = γ' = 75.52224878141° = 75°31'21″ = 1.82334765819 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.