# 4 16 16 triangle

### Acute isosceles triangle.

Sides: a = 4   b = 16   c = 16

Area: T = 31.74990157328
Perimeter: p = 36
Semiperimeter: s = 18

Angle ∠ A = α = 14.36215115629° = 14°21'41″ = 0.25106556623 rad
Angle ∠ B = β = 82.81992442185° = 82°49'9″ = 1.44554684956 rad
Angle ∠ C = γ = 82.81992442185° = 82°49'9″ = 1.44554684956 rad

Height: ha = 15.87545078664
Height: hb = 3.96986269666
Height: hc = 3.96986269666

Median: ma = 15.87545078664
Median: mb = 8.48552813742
Median: mc = 8.48552813742

Inradius: r = 1.76438342074
Circumradius: R = 8.06332420909

Vertex coordinates: A[16; 0] B[0; 0] C[0.5; 3.96986269666]
Centroid: CG[5.5; 1.32328756555]
Coordinates of the circumscribed circle: U[8; 1.00879052614]
Coordinates of the inscribed circle: I[2; 1.76438342074]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 165.6388488437° = 165°38'19″ = 0.25106556623 rad
∠ B' = β' = 97.18107557815° = 97°10'51″ = 1.44554684956 rad
∠ C' = γ' = 97.18107557815° = 97°10'51″ = 1.44554684956 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    