# 11 13 20 triangle

### Obtuse scalene triangle.

Sides: a = 11   b = 13   c = 20

Area: T = 66
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 30.51102374061° = 30°30'37″ = 0.53325040983 rad
Angle ∠ B = β = 36.87698976458° = 36°52'12″ = 0.64435011088 rad
Angle ∠ C = γ = 112.6219864948° = 112°37'11″ = 1.96655874465 rad

Height: ha = 12
Height: hb = 10.15438461538
Height: hc = 6.6

Median: ma = 15.94552187191
Median: mb = 14.77332867027
Median: mc = 6.70882039325

Inradius: r = 3
Circumradius: R = 10.83333333333

Vertex coordinates: A[20; 0] B[0; 0] C[8.8; 6.6]
Centroid: CG[9.6; 2.2]
Coordinates of the circumscribed circle: U[10; -4.16766666667]
Coordinates of the inscribed circle: I[9; 3]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 149.4989762594° = 149°29'23″ = 0.53325040983 rad
∠ B' = β' = 143.1330102354° = 143°7'48″ = 0.64435011088 rad
∠ C' = γ' = 67.3880135052° = 67°22'49″ = 1.96655874465 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.