# 13 16 28 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 16   c = 28

Area: T = 52.54546238925
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 13.56765254723° = 13°34' = 0.23767805375 rad
Angle ∠ B = β = 16.78105453515° = 16°46'50″ = 0.29328757667 rad
Angle ∠ C = γ = 149.6532929176° = 149°39'11″ = 2.61219363494 rad

Height: ha = 8.08437882911
Height: hb = 6.56880779866
Height: hc = 3.75331874209

Median: ma = 21.85774929944
Median: mb = 20.31100960116
Median: mc = 4.06220192023

Inradius: r = 1.84436710138
Circumradius: R = 27.71097806044

Vertex coordinates: A[28; 0] B[0; 0] C[12.44664285714; 3.75331874209]
Centroid: CG[13.48221428571; 1.25110624736]
Coordinates of the circumscribed circle: U[14; -23.91330077812]
Coordinates of the inscribed circle: I[12.5; 1.84436710138]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.4333474528° = 166°26' = 0.23767805375 rad
∠ B' = β' = 163.2199454648° = 163°13'10″ = 0.29328757667 rad
∠ C' = γ' = 30.34770708239° = 30°20'49″ = 2.61219363494 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    