# 13 16 16 triangle

### Acute isosceles triangle.

Sides: a = 13   b = 16   c = 16

Area: T = 95.03112448619
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 47.93989646355° = 47°56'20″ = 0.83766927729 rad
Angle ∠ B = β = 66.03105176822° = 66°1'50″ = 1.15224499404 rad
Angle ∠ C = γ = 66.03105176822° = 66°1'50″ = 1.15224499404 rad

Height: ha = 14.62201915172
Height: hb = 11.87989056077
Height: hc = 11.87989056077

Median: ma = 14.62201915172
Median: mb = 12.1866057607
Median: mc = 12.1866057607

Inradius: r = 4.22436108828
Circumradius: R = 8.75550152711

Vertex coordinates: A[16; 0] B[0; 0] C[5.281125; 11.87989056077]
Centroid: CG[7.094375; 3.96596352026]
Coordinates of the circumscribed circle: U[8; 3.55767249539]
Coordinates of the inscribed circle: I[6.5; 4.22436108828]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 132.0611035364° = 132°3'40″ = 0.83766927729 rad
∠ B' = β' = 113.9699482318° = 113°58'10″ = 1.15224499404 rad
∠ C' = γ' = 113.9699482318° = 113°58'10″ = 1.15224499404 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    