# 12 18 25 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 18   c = 25

Area: T = 100.6155294563
Perimeter: p = 55
Semiperimeter: s = 27.5

Angle ∠ A = α = 26.56328406278° = 26°33'46″ = 0.46436090276 rad
Angle ∠ B = β = 42.12664158149° = 42°7'35″ = 0.7355244658 rad
Angle ∠ C = γ = 111.3110743557° = 111°18'39″ = 1.94327389679 rad

Height: ha = 16.76992157605
Height: hb = 11.17994771737
Height: hc = 8.0499223565

Median: ma = 20.94403915914
Median: mb = 17.42112513902
Median: mc = 8.81875960443

Inradius: r = 3.65987379841
Circumradius: R = 13.41774432015

Vertex coordinates: A[25; 0] B[0; 0] C[8.9; 8.0499223565]
Centroid: CG[11.3; 2.68330745217]
Coordinates of the circumscribed circle: U[12.5; -4.87662467191]
Coordinates of the inscribed circle: I[9.5; 3.65987379841]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 153.4377159372° = 153°26'14″ = 0.46436090276 rad
∠ B' = β' = 137.8743584185° = 137°52'25″ = 0.7355244658 rad
∠ C' = γ' = 68.68992564427° = 68°41'21″ = 1.94327389679 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.