# 19 20 20 triangle

### Acute isosceles triangle.

Sides: a = 19   b = 20   c = 20

Area: T = 167.1977301115
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 56.71987000563° = 56°43'7″ = 0.99899280634 rad
Angle ∠ B = β = 61.64106499718° = 61°38'26″ = 1.07658322951 rad
Angle ∠ C = γ = 61.64106499718° = 61°38'26″ = 1.07658322951 rad

Height: ha = 17.65997159068
Height: hb = 16.72197301115
Height: hc = 16.72197301115

Median: ma = 17.65997159068
Median: mb = 16.74881342244
Median: mc = 16.74881342244

Inradius: r = 5.66877051225
Circumradius: R = 11.36438197945

Vertex coordinates: A[20; 0] B[0; 0] C[9.025; 16.72197301115]
Centroid: CG[9.675; 5.57332433705]
Coordinates of the circumscribed circle: U[10; 5.39878144024]
Coordinates of the inscribed circle: I[9.5; 5.66877051225]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 123.2811299944° = 123°16'53″ = 0.99899280634 rad
∠ B' = β' = 118.3599350028° = 118°21'34″ = 1.07658322951 rad
∠ C' = γ' = 118.3599350028° = 118°21'34″ = 1.07658322951 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.