# 21 28 29 triangle

### Acute scalene triangle.

Sides: a = 21   b = 28   c = 29

Area: T = 277.8854868246
Perimeter: p = 78
Semiperimeter: s = 39

Angle ∠ A = α = 43.19220135372° = 43°11'31″ = 0.75438428468 rad
Angle ∠ B = β = 65.86663189457° = 65°51'59″ = 1.15495841318 rad
Angle ∠ C = γ = 70.94216675171° = 70°56'30″ = 1.2388165675 rad

Height: ha = 26.46552255472
Height: hb = 19.84989191604
Height: hc = 19.16444736721

Median: ma = 26.5
Median: mb = 21.09550231097
Median: mc = 20.05661711201

Inradius: r = 7.12552530319
Circumradius: R = 15.34108856945

Vertex coordinates: A[29; 0] B[0; 0] C[8.58662068966; 19.16444736721]
Centroid: CG[12.52987356322; 6.38881578907]
Coordinates of the circumscribed circle: U[14.5; 5.00992687982]
Coordinates of the inscribed circle: I[11; 7.12552530319]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 136.8087986463° = 136°48'29″ = 0.75438428468 rad
∠ B' = β' = 114.1343681054° = 114°8'1″ = 1.15495841318 rad
∠ C' = γ' = 109.0588332483° = 109°3'30″ = 1.2388165675 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.