# 25 26 30 triangle

### Acute scalene triangle.

Sides: a = 25   b = 26   c = 30

Area: T = 309.1521965059
Perimeter: p = 81
Semiperimeter: s = 40.5

Angle ∠ A = α = 52.43883020381° = 52°26'18″ = 0.91552210247 rad
Angle ∠ B = β = 55.52882380553° = 55°31'42″ = 0.96991505819 rad
Angle ∠ C = γ = 72.03334599066° = 72°2' = 1.2577221047 rad

Height: ha = 24.73221572047
Height: hb = 23.78109203892
Height: hc = 20.6110131004

Median: ma = 25.13546374551
Median: mb = 24.36218554302
Median: mc = 20.62876513447

Inradius: r = 7.63333818533
Circumradius: R = 15.76989439207

Vertex coordinates: A[30; 0] B[0; 0] C[14.15; 20.6110131004]
Centroid: CG[14.71766666667; 6.8770043668]
Coordinates of the circumscribed circle: U[15; 4.86441127017]
Coordinates of the inscribed circle: I[14.5; 7.63333818533]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 127.5621697962° = 127°33'42″ = 0.91552210247 rad
∠ B' = β' = 124.4721761945° = 124°28'18″ = 0.96991505819 rad
∠ C' = γ' = 107.9676540093° = 107°58' = 1.2577221047 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    