# 14 20 20 triangle

### Acute isosceles triangle.

Sides: a = 14   b = 20   c = 20

Area: T = 131.1454957966
Perimeter: p = 54
Semiperimeter: s = 27

Angle ∠ A = α = 40.97546302294° = 40°58'29″ = 0.71551422073 rad
Angle ∠ B = β = 69.51326848853° = 69°30'46″ = 1.21332252231 rad
Angle ∠ C = γ = 69.51326848853° = 69°30'46″ = 1.21332252231 rad

Height: ha = 18.73549939952
Height: hb = 13.11444957966
Height: hc = 13.11444957966

Median: ma = 18.73549939952
Median: mb = 14.07112472795
Median: mc = 14.07112472795

Inradius: r = 4.85772206654
Circumradius: R = 10.67552102537

Vertex coordinates: A[20; 0] B[0; 0] C[4.9; 13.11444957966]
Centroid: CG[8.3; 4.37114985989]
Coordinates of the circumscribed circle: U[10; 3.73663235888]
Coordinates of the inscribed circle: I[7; 4.85772206654]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 139.0255369771° = 139°1'31″ = 0.71551422073 rad
∠ B' = β' = 110.4877315115° = 110°29'14″ = 1.21332252231 rad
∠ C' = γ' = 110.4877315115° = 110°29'14″ = 1.21332252231 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    