# 3 20 20 triangle

### Acute isosceles triangle.

Sides: a = 3   b = 20   c = 20

Area: T = 29.91655060128
Perimeter: p = 43
Semiperimeter: s = 21.5

Angle ∠ A = α = 8.60224446093° = 8°36'9″ = 0.15501409822 rad
Angle ∠ B = β = 85.69987776953° = 85°41'56″ = 1.49657258357 rad
Angle ∠ C = γ = 85.69987776953° = 85°41'56″ = 1.49657258357 rad

Height: ha = 19.94436706752
Height: hb = 2.99215506013
Height: hc = 2.99215506013

Median: ma = 19.94436706752
Median: mb = 10.22325241501
Median: mc = 10.22325241501

Inradius: r = 1.39114188843
Circumradius: R = 10.02882442113

Vertex coordinates: A[20; 0] B[0; 0] C[0.225; 2.99215506013]
Centroid: CG[6.74216666667; 0.99771835338]
Coordinates of the circumscribed circle: U[10; 0.75221183158]
Coordinates of the inscribed circle: I[1.5; 1.39114188843]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 171.3987555391° = 171°23'51″ = 0.15501409822 rad
∠ B' = β' = 94.30112223047° = 94°18'4″ = 1.49657258357 rad
∠ C' = γ' = 94.30112223047° = 94°18'4″ = 1.49657258357 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.