# 13 17 20 triangle

### Acute scalene triangle.

Sides: a = 13   b = 17   c = 20

Area: T = 109.5454511501
Perimeter: p = 50
Semiperimeter: s = 25

Angle ∠ A = α = 40.11991668984° = 40°7'9″ = 0.77002115555 rad
Angle ∠ B = β = 57.42110296072° = 57°25'16″ = 1.00221860265 rad
Angle ∠ C = γ = 82.46598034944° = 82°27'35″ = 1.43991950715 rad

Height: ha = 16.85330017694
Height: hb = 12.88875895884
Height: hc = 10.95444511501

Median: ma = 17.38553386507
Median: mb = 14.56988022843
Median: mc = 11.35878166916

Inradius: r = 4.382178046
Circumradius: R = 10.08772237674

Vertex coordinates: A[20; 0] B[0; 0] C[7; 10.95444511501]
Centroid: CG[9; 3.65114837167]
Coordinates of the circumscribed circle: U[10; 1.32436628473]
Coordinates of the inscribed circle: I[8; 4.382178046]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 139.8810833102° = 139°52'51″ = 0.77002115555 rad
∠ B' = β' = 122.5798970393° = 122°34'44″ = 1.00221860265 rad
∠ C' = γ' = 97.54401965056° = 97°32'25″ = 1.43991950715 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.