# 20 25 28 triangle

### Acute scalene triangle.

Sides: a = 20   b = 25   c = 28

Area: T = 242.6311278899
Perimeter: p = 73
Semiperimeter: s = 36.5

Angle ∠ A = α = 43.88765152837° = 43°53'11″ = 0.76659641889 rad
Angle ∠ B = β = 60.05990533933° = 60°3'33″ = 1.04882282273 rad
Angle ∠ C = γ = 76.0544431323° = 76°3'16″ = 1.32774002373 rad

Height: ha = 24.26331278899
Height: hb = 19.41105023119
Height: hc = 17.33108056356

Median: ma = 24.58765817063
Median: mb = 20.87546257451
Median: mc = 17.79904468747

Inradius: r = 6.64774322986
Circumradius: R = 14.42551805286

Vertex coordinates: A[28; 0] B[0; 0] C[9.98221428571; 17.33108056356]
Centroid: CG[12.66107142857; 5.77769352119]
Coordinates of the circumscribed circle: U[14; 3.47664685074]
Coordinates of the inscribed circle: I[11.5; 6.64774322986]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 136.1133484716° = 136°6'49″ = 0.76659641889 rad
∠ B' = β' = 119.9410946607° = 119°56'27″ = 1.04882282273 rad
∠ C' = γ' = 103.9465568677° = 103°56'44″ = 1.32774002373 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.