# 13 22 28 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 22   c = 28

Area: T = 139.1999272627
Perimeter: p = 63
Semiperimeter: s = 31.5

Angle ∠ A = α = 26.86985861119° = 26°52'7″ = 0.4698945293 rad
Angle ∠ B = β = 49.89219743369° = 49°53'31″ = 0.87107792225 rad
Angle ∠ C = γ = 103.2399439551° = 103°14'22″ = 1.80218681381 rad

Height: ha = 21.41552727119
Height: hb = 12.65444793298
Height: hc = 9.94328051877

Median: ma = 24.32659121103
Median: mb = 18.8554707635
Median: mc = 11.42436596588

Inradius: r = 4.41990245279
Circumradius: R = 14.38222590608

Vertex coordinates: A[28; 0] B[0; 0] C[8.375; 9.94328051877]
Centroid: CG[12.125; 3.31442683959]
Coordinates of the circumscribed circle: U[14; -3.29438390506]
Coordinates of the inscribed circle: I[9.5; 4.41990245279]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 153.1311413888° = 153°7'53″ = 0.4698945293 rad
∠ B' = β' = 130.1088025663° = 130°6'29″ = 0.87107792225 rad
∠ C' = γ' = 76.76105604487° = 76°45'38″ = 1.80218681381 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    