# 13 18 25 triangle

### Obtuse scalene triangle.

Sides: a = 13   b = 18   c = 25

Area: T = 112.2549721603
Perimeter: p = 56
Semiperimeter: s = 28

Angle ∠ A = α = 29.92664348666° = 29°55'35″ = 0.52223148218 rad
Angle ∠ B = β = 43.69108952793° = 43°41'27″ = 0.76325499758 rad
Angle ∠ C = γ = 106.3832669854° = 106°22'58″ = 1.8576727856 rad

Height: ha = 17.2699187939
Height: hb = 12.47221912892
Height: hc = 8.98799777283

Median: ma = 20.79106228863
Median: mb = 17.77663888346
Median: mc = 9.5

Inradius: r = 4.00989186287
Circumradius: R = 13.02989855432

Vertex coordinates: A[25; 0] B[0; 0] C[9.4; 8.98799777283]
Centroid: CG[11.46766666667; 2.99333259094]
Coordinates of the circumscribed circle: U[12.5; -3.67548420763]
Coordinates of the inscribed circle: I[10; 4.00989186287]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 150.0743565133° = 150°4'25″ = 0.52223148218 rad
∠ B' = β' = 136.3099104721° = 136°18'33″ = 0.76325499758 rad
∠ C' = γ' = 73.61773301459° = 73°37'2″ = 1.8576727856 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.