# 21 24 28 triangle

### Acute scalene triangle.

Sides: a = 21   b = 24   c = 28

Area: T = 245.1755319924
Perimeter: p = 73
Semiperimeter: s = 36.5

Angle ∠ A = α = 46.86602822563° = 46°51'37″ = 0.81878662138 rad
Angle ∠ B = β = 56.50545509846° = 56°30'16″ = 0.9866190457 rad
Angle ∠ C = γ = 76.63551667591° = 76°38'7″ = 1.33875359828 rad

Height: ha = 23.3550030469
Height: hb = 20.43112766604
Height: hc = 17.51325228517

Median: ma = 23.86994365246
Median: mb = 21.64548608219
Median: mc = 17.67876695297

Inradius: r = 6.71771320527
Circumradius: R = 14.39897028506

Vertex coordinates: A[28; 0] B[0; 0] C[11.58992857143; 17.51325228517]
Centroid: CG[13.19664285714; 5.83875076172]
Coordinates of the circumscribed circle: U[14; 3.32661912343]
Coordinates of the inscribed circle: I[12.5; 6.71771320527]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.1439717744° = 133°8'23″ = 0.81878662138 rad
∠ B' = β' = 123.4955449015° = 123°29'44″ = 0.9866190457 rad
∠ C' = γ' = 103.3654833241° = 103°21'53″ = 1.33875359828 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.