# 11 12 20 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 12   c = 20

Area: T = 56.71880526817
Perimeter: p = 43
Semiperimeter: s = 21.5

Angle ∠ A = α = 28.20664802662° = 28°12'23″ = 0.4922295951 rad
Angle ∠ B = β = 31.03988161007° = 31°2'20″ = 0.54217295369 rad
Angle ∠ C = γ = 120.7554703633° = 120°45'17″ = 2.10875671657 rad

Height: ha = 10.31223732148
Height: hb = 9.45330087803
Height: hc = 5.67218052682

Median: ma = 15.54883118055
Median: mb = 14.98333240638
Median: mc = 5.70108771255

Inradius: r = 2.63880489619
Circumradius: R = 11.63765066993

Vertex coordinates: A[20; 0] B[0; 0] C[9.425; 5.67218052682]
Centroid: CG[9.80883333333; 1.89106017561]
Coordinates of the circumscribed circle: U[10; -5.95504863803]
Coordinates of the inscribed circle: I[9.5; 2.63880489619]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.7943519734° = 151°47'37″ = 0.4922295951 rad
∠ B' = β' = 148.9611183899° = 148°57'40″ = 0.54217295369 rad
∠ C' = γ' = 59.2455296367° = 59°14'43″ = 2.10875671657 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.