# 20 28 30 triangle

### Acute scalene triangle.

Sides: a = 20   b = 28   c = 30

Area: T = 270.8498666233
Perimeter: p = 78
Semiperimeter: s = 39

Angle ∠ A = α = 40.15765122086° = 40°9'23″ = 0.70108633542 rad
Angle ∠ B = β = 64.53224398575° = 64°31'57″ = 1.12663035499 rad
Angle ∠ C = γ = 75.31110479339° = 75°18'40″ = 1.31444257496 rad

Height: ha = 27.08548666233
Height: hb = 19.34663333023
Height: hc = 18.05765777488

Median: ma = 27.24396769438
Median: mb = 21.30772757527
Median: mc = 19.15772440607

Inradius: r = 6.94548375957
Circumradius: R = 15.50768144083

Vertex coordinates: A[30; 0] B[0; 0] C[8.6; 18.05765777488]
Centroid: CG[12.86766666667; 6.01988592496]
Coordinates of the circumscribed circle: U[15; 3.93220850821]
Coordinates of the inscribed circle: I[11; 6.94548375957]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 139.8433487791° = 139°50'37″ = 0.70108633542 rad
∠ B' = β' = 115.4687560142° = 115°28'3″ = 1.12663035499 rad
∠ C' = γ' = 104.6898952066° = 104°41'20″ = 1.31444257496 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.