# 12 25 30 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 25   c = 30

Area: T = 146.3811137788
Perimeter: p = 67
Semiperimeter: s = 33.5

Angle ∠ A = α = 22.97662605514° = 22°58'35″ = 0.40110113964 rad
Angle ∠ B = β = 54.41325789652° = 54°24'45″ = 0.95496786574 rad
Angle ∠ C = γ = 102.6111160483° = 102°36'40″ = 1.79109025997 rad

Height: ha = 24.39768562979
Height: hb = 11.7110491023
Height: hc = 9.75987425192

Median: ma = 26.95436639439
Median: mb = 19.12545914989
Median: mc = 12.62993309403

Inradius: r = 4.37695862026
Circumradius: R = 15.37108328409

Vertex coordinates: A[30; 0] B[0; 0] C[6.98333333333; 9.75987425192]
Centroid: CG[12.32877777778; 3.25329141731]
Coordinates of the circumscribed circle: U[15; -3.35659651703]
Coordinates of the inscribed circle: I[8.5; 4.37695862026]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.0243739449° = 157°1'25″ = 0.40110113964 rad
∠ B' = β' = 125.5877421035° = 125°35'15″ = 0.95496786574 rad
∠ C' = γ' = 77.38988395165° = 77°23'20″ = 1.79109025997 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.