# 20 21 26 triangle

### Acute scalene triangle.

Sides: a = 20   b = 21   c = 26

Area: T = 205.9098808699
Perimeter: p = 67
Semiperimeter: s = 33.5

Angle ∠ A = α = 48.95994188107° = 48°57'34″ = 0.85545030581 rad
Angle ∠ B = β = 52.36987700413° = 52°22'8″ = 0.91440074624 rad
Angle ∠ C = γ = 78.67218111479° = 78°40'19″ = 1.3733082133 rad

Height: ha = 20.59108808699
Height: hb = 19.61103627333
Height: hc = 15.83991391307

Median: ma = 21.41326131054
Median: mb = 20.68221178799
Median: mc = 15.85987515272

Inradius: r = 6.1476531603
Circumradius: R = 13.25882963169

Vertex coordinates: A[26; 0] B[0; 0] C[12.21215384615; 15.83991391307]
Centroid: CG[12.73771794872; 5.28797130436]
Coordinates of the circumscribed circle: U[13; 2.60443082051]
Coordinates of the inscribed circle: I[12.5; 6.1476531603]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 131.0410581189° = 131°2'26″ = 0.85545030581 rad
∠ B' = β' = 127.6311229959° = 127°37'52″ = 0.91440074624 rad
∠ C' = γ' = 101.3288188852° = 101°19'41″ = 1.3733082133 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.