# 12 13 17 triangle

### Acute scalene triangle.

Sides: a = 12   b = 13   c = 17

Area: T = 77.76988883809
Perimeter: p = 42
Semiperimeter: s = 21

Angle ∠ A = α = 44.73219408557° = 44°43'55″ = 0.78107196487 rad
Angle ∠ B = β = 49.687978493° = 49°40'47″ = 0.86770758187 rad
Angle ∠ C = γ = 85.58882742142° = 85°35'18″ = 1.49437971861 rad

Height: ha = 12.96114813968
Height: hb = 11.96444443663
Height: hc = 9.1499280986

Median: ma = 13.89224439894
Median: mb = 13.22003787824
Median: mc = 9.17987798753

Inradius: r = 3.70332803991
Circumradius: R = 8.52552600854

Vertex coordinates: A[17; 0] B[0; 0] C[7.76547058824; 9.1499280986]
Centroid: CG[8.25549019608; 3.05497603287]
Coordinates of the circumscribed circle: U[8.5; 0.65657892373]
Coordinates of the inscribed circle: I[8; 3.70332803991]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 135.2688059144° = 135°16'5″ = 0.78107196487 rad
∠ B' = β' = 130.322021507° = 130°19'13″ = 0.86770758187 rad
∠ C' = γ' = 94.41217257858° = 94°24'42″ = 1.49437971861 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.