# 8 17 20 triangle

### Obtuse scalene triangle.

Sides: a = 8   b = 17   c = 20

Area: T = 66.97771416231
Perimeter: p = 45
Semiperimeter: s = 22.5

Angle ∠ A = α = 23.20325730572° = 23°12'9″ = 0.40549612948 rad
Angle ∠ B = β = 56.84771120714° = 56°50'50″ = 0.99221692759 rad
Angle ∠ C = γ = 99.95503148714° = 99°57'1″ = 1.74444620829 rad

Height: ha = 16.74442854058
Height: hb = 7.88796637204
Height: hc = 6.69877141623

Median: ma = 18.12545689604
Median: mb = 12.63992246598
Median: mc = 8.74664278423

Inradius: r = 2.97767618499
Circumradius: R = 10.1532717532

Vertex coordinates: A[20; 0] B[0; 0] C[4.375; 6.69877141623]
Centroid: CG[8.125; 2.23325713874]
Coordinates of the circumscribed circle: U[10; -1.75443298677]
Coordinates of the inscribed circle: I[5.5; 2.97767618499]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 156.7977426943° = 156°47'51″ = 0.40549612948 rad
∠ B' = β' = 123.1532887929° = 123°9'10″ = 0.99221692759 rad
∠ C' = γ' = 80.05496851286° = 80°2'59″ = 1.74444620829 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.