# 11 20 20 triangle

### Acute isosceles triangle.

Sides: a = 11   b = 20   c = 20

Area: T = 105.7598864877
Perimeter: p = 51
Semiperimeter: s = 25.5

Angle ∠ A = α = 31.92440283257° = 31°55'27″ = 0.55771794048 rad
Angle ∠ B = β = 74.03879858372° = 74°2'17″ = 1.29222066244 rad
Angle ∠ C = γ = 74.03879858372° = 74°2'17″ = 1.29222066244 rad

Height: ha = 19.2298884523
Height: hb = 10.57658864877
Height: hc = 10.57658864877

Median: ma = 19.2298884523
Median: mb = 12.66988594593
Median: mc = 12.66988594593

Inradius: r = 4.14774064658
Circumradius: R = 10.40110193498

Vertex coordinates: A[20; 0] B[0; 0] C[3.025; 10.57658864877]
Centroid: CG[7.675; 3.52552954959]
Coordinates of the circumscribed circle: U[10; 2.86602803212]
Coordinates of the inscribed circle: I[5.5; 4.14774064658]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.0765971674° = 148°4'33″ = 0.55771794048 rad
∠ B' = β' = 105.9622014163° = 105°57'43″ = 1.29222066244 rad
∠ C' = γ' = 105.9622014163° = 105°57'43″ = 1.29222066244 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.