# 21 22 26 triangle

### Acute scalene triangle.

Sides: a = 21   b = 22   c = 26

Area: T = 222.454434925
Perimeter: p = 69
Semiperimeter: s = 34.5

Angle ∠ A = α = 51.06107158057° = 51°3'39″ = 0.89111776092 rad
Angle ∠ B = β = 54.57326412751° = 54°34'22″ = 0.95224722718 rad
Angle ∠ C = γ = 74.36766429192° = 74°22' = 1.29879427726 rad

Height: ha = 21.18661284999
Height: hb = 20.2233122659
Height: hc = 17.11218730192

Median: ma = 21.67437168017
Median: mb = 20.91765006634
Median: mc = 17.1321841699

Inradius: r = 6.44879521522
Circumradius: R = 13.4999398911

Vertex coordinates: A[26; 0] B[0; 0] C[12.17330769231; 17.11218730192]
Centroid: CG[12.72443589744; 5.70439576731]
Coordinates of the circumscribed circle: U[13; 3.63878250312]
Coordinates of the inscribed circle: I[12.5; 6.44879521522]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 128.9399284194° = 128°56'21″ = 0.89111776092 rad
∠ B' = β' = 125.4277358725° = 125°25'38″ = 0.95224722718 rad
∠ C' = γ' = 105.6333357081° = 105°38' = 1.29879427726 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    