# 12 17 26 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 17   c = 26

Area: T = 81.93655691992
Perimeter: p = 55
Semiperimeter: s = 27.5

Angle ∠ A = α = 21.76218286861° = 21°45'43″ = 0.38798155618 rad
Angle ∠ B = β = 31.68435938865° = 31°41'1″ = 0.55329830322 rad
Angle ∠ C = γ = 126.5554577427° = 126°33'16″ = 2.20987940596 rad

Height: ha = 13.65659281999
Height: hb = 9.63994787293
Height: hc = 6.30327360922

Median: ma = 21.13105466091
Median: mb = 18.37879759495
Median: mc = 6.8922024376

Inradius: r = 2.97994752436
Circumradius: R = 16.18334477134

Vertex coordinates: A[26; 0] B[0; 0] C[10.21215384615; 6.30327360922]
Centroid: CG[12.07105128205; 2.10109120307]
Coordinates of the circumscribed circle: U[13; -9.63986710646]
Coordinates of the inscribed circle: I[10.5; 2.97994752436]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 158.2388171314° = 158°14'17″ = 0.38798155618 rad
∠ B' = β' = 148.3166406113° = 148°18'59″ = 0.55329830322 rad
∠ C' = γ' = 53.44554225727° = 53°26'44″ = 2.20987940596 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.