# 3 13 15 triangle

### Obtuse scalene triangle.

Sides: a = 3   b = 13   c = 15

Area: T = 15.56223744975
Perimeter: p = 31
Semiperimeter: s = 15.5

Angle ∠ A = α = 9.18444977727° = 9°11'4″ = 0.16602997263 rad
Angle ∠ B = β = 43.76217426927° = 43°45'42″ = 0.76437864964 rad
Angle ∠ C = γ = 127.0543759535° = 127°3'14″ = 2.21875064309 rad

Height: ha = 10.37549163317
Height: hb = 2.39442114612
Height: hc = 2.07549832663

Median: ma = 13.9555285737
Median: mb = 8.64658082329
Median: mc = 5.72327615711

Inradius: r = 1.00440241611
Circumradius: R = 9.39876661482

Vertex coordinates: A[15; 0] B[0; 0] C[2.16766666667; 2.07549832663]
Centroid: CG[5.72222222222; 0.69216610888]
Coordinates of the circumscribed circle: U[7.5; -5.66326962688]
Coordinates of the inscribed circle: I[2.5; 1.00440241611]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 170.8165502227° = 170°48'56″ = 0.16602997263 rad
∠ B' = β' = 136.2388257307° = 136°14'18″ = 0.76437864964 rad
∠ C' = γ' = 52.94662404654° = 52°56'46″ = 2.21875064309 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.