# 4 20 20 triangle

### Acute isosceles triangle.

Sides: a = 4   b = 20   c = 20

Area: T = 39.79994974843
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 11.47883409545° = 11°28'42″ = 0.22003348423 rad
Angle ∠ B = β = 84.26108295227° = 84°15'39″ = 1.47106289056 rad
Angle ∠ C = γ = 84.26108295227° = 84°15'39″ = 1.47106289056 rad

Height: ha = 19.98997487421
Height: hb = 3.98799497484
Height: hc = 3.98799497484

Median: ma = 19.98997487421
Median: mb = 10.39223048454
Median: mc = 10.39223048454

Inradius: r = 1.80990680675
Circumradius: R = 10.05503781526

Vertex coordinates: A[20; 0] B[0; 0] C[0.4; 3.98799497484]
Centroid: CG[6.8; 1.32766499161]
Coordinates of the circumscribed circle: U[10; 1.00550378153]
Coordinates of the inscribed circle: I[2; 1.80990680675]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 168.5221659045° = 168°31'18″ = 0.22003348423 rad
∠ B' = β' = 95.73991704773° = 95°44'21″ = 1.47106289056 rad
∠ C' = γ' = 95.73991704773° = 95°44'21″ = 1.47106289056 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.