# 12 28 30 triangle

### Acute scalene triangle.

Sides: a = 12   b = 28   c = 30

Area: T = 167.8544103316
Perimeter: p = 70
Semiperimeter: s = 35

Angle ∠ A = α = 23.55664643091° = 23°33'23″ = 0.41111378623 rad
Angle ∠ B = β = 68.83215511542° = 68°49'54″ = 1.20113371969 rad
Angle ∠ C = γ = 87.61219845367° = 87°36'43″ = 1.52991175944 rad

Height: ha = 27.9765683886
Height: hb = 11.99895788083
Height: hc = 11.19902735544

Median: ma = 28.39901391332
Median: mb = 18.05554700853
Median: mc = 15.46596248337

Inradius: r = 4.79658315233
Circumradius: R = 15.01330378121

Vertex coordinates: A[30; 0] B[0; 0] C[4.33333333333; 11.19902735544]
Centroid: CG[11.44444444444; 3.73300911848]
Coordinates of the circumscribed circle: U[15; 0.62655432422]
Coordinates of the inscribed circle: I[7; 4.79658315233]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 156.4443535691° = 156°26'37″ = 0.41111378623 rad
∠ B' = β' = 111.1688448846° = 111°10'6″ = 1.20113371969 rad
∠ C' = γ' = 92.38880154633° = 92°23'17″ = 1.52991175944 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.