# 12 15 26 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 15   c = 26

Area: T = 47.00546540249
Perimeter: p = 53
Semiperimeter: s = 26.5

Angle ∠ A = α = 13.9488491432° = 13°56'55″ = 0.24334471012 rad
Angle ∠ B = β = 17.53664150077° = 17°32'11″ = 0.30660681809 rad
Angle ∠ C = γ = 148.515509356° = 148°30'54″ = 2.59220773715 rad

Height: ha = 7.83441090041
Height: hb = 6.26772872033
Height: hc = 3.61657426173

Median: ma = 20.35992730715
Median: mb = 18.80882428738
Median: mc = 3.9377003937

Inradius: r = 1.77437605292
Circumradius: R = 24.89111522544

Vertex coordinates: A[26; 0] B[0; 0] C[11.44223076923; 3.61657426173]
Centroid: CG[12.48107692308; 1.20552475391]
Coordinates of the circumscribed circle: U[13; -21.22766215059]
Coordinates of the inscribed circle: I[11.5; 1.77437605292]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.0521508568° = 166°3'5″ = 0.24334471012 rad
∠ B' = β' = 162.4643584992° = 162°27'49″ = 0.30660681809 rad
∠ C' = γ' = 31.48549064397° = 31°29'6″ = 2.59220773715 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.