# 5 17 20 triangle

### Obtuse scalene triangle.

Sides: a = 5   b = 17   c = 20

Area: T = 36.66106055596
Perimeter: p = 42
Semiperimeter: s = 21

Angle ∠ A = α = 12.45437005943° = 12°27'13″ = 0.21773580794 rad
Angle ∠ B = β = 47.15663569564° = 47°9'23″ = 0.82330336921 rad
Angle ∠ C = γ = 120.3989942449° = 120°23'24″ = 2.1011200882 rad

Height: ha = 14.66442422239
Height: hb = 4.31330124188
Height: hc = 3.6666060556

Median: ma = 18.39215741577
Median: mb = 11.84327192823
Median: mc = 7.55498344353

Inradius: r = 1.74657431219
Circumradius: R = 11.59328254188

Vertex coordinates: A[20; 0] B[0; 0] C[3.4; 3.6666060556]
Centroid: CG[7.8; 1.22220201853]
Coordinates of the circumscribed circle: U[10; -5.86546058001]
Coordinates of the inscribed circle: I[4; 1.74657431219]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.5466299406° = 167°32'47″ = 0.21773580794 rad
∠ B' = β' = 132.8443643044° = 132°50'37″ = 0.82330336921 rad
∠ C' = γ' = 59.61100575507° = 59°36'36″ = 2.1011200882 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.