# 21 25 30 triangle

### Acute scalene triangle.

Sides: a = 21   b = 25   c = 30

Area: T = 259.1998765429
Perimeter: p = 76
Semiperimeter: s = 38

Angle ∠ A = α = 43.72549134683° = 43°43'30″ = 0.76331437052 rad
Angle ∠ B = β = 55.37114408187° = 55°22'17″ = 0.96664139539 rad
Angle ∠ C = γ = 80.9043645713° = 80°54'13″ = 1.41220349946 rad

Height: ha = 24.68655967075
Height: hb = 20.73659012343
Height: hc = 17.28799176953

Median: ma = 25.53991855782
Median: mb = 22.67770809409
Median: mc = 17.55499287748

Inradius: r = 6.82110201429
Circumradius: R = 15.19110445772

Vertex coordinates: A[30; 0] B[0; 0] C[11.93333333333; 17.28799176953]
Centroid: CG[13.97877777778; 5.76599725651]
Coordinates of the circumscribed circle: U[15; 2.40216318094]
Coordinates of the inscribed circle: I[13; 6.82110201429]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 136.2755086532° = 136°16'30″ = 0.76331437052 rad
∠ B' = β' = 124.6298559181° = 124°37'43″ = 0.96664139539 rad
∠ C' = γ' = 99.0966354287° = 99°5'47″ = 1.41220349946 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.