# 13 15 25 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 15   c = 25

Area: T = 78.55769061254
Perimeter: p = 53
Semiperimeter: s = 26.5

Angle ∠ A = α = 24.77695868266° = 24°46'11″ = 0.43223108445 rad
Angle ∠ B = β = 28.90994725423° = 28°54'34″ = 0.50545654809 rad
Angle ∠ C = γ = 126.3210940631° = 126°19'15″ = 2.20547163282 rad

Height: ha = 12.08656778655
Height: hb = 10.47442541501
Height: hc = 6.285455249

Median: ma = 19.56439975465
Median: mb = 18.4599414942
Median: mc = 6.38435726674

Inradius: r = 2.96444115519
Circumradius: R = 15.51442311493

Vertex coordinates: A[25; 0] B[0; 0] C[11.38; 6.285455249]
Centroid: CG[12.12766666667; 2.095485083]
Coordinates of the circumscribed circle: U[12.5; -9.18991984499]
Coordinates of the inscribed circle: I[11.5; 2.96444115519]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 155.2330413173° = 155°13'49″ = 0.43223108445 rad
∠ B' = β' = 151.0910527458° = 151°5'26″ = 0.50545654809 rad
∠ C' = γ' = 53.67990593689° = 53°40'45″ = 2.20547163282 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.