# 21 25 26 triangle

### Acute scalene triangle.

Sides: a = 21   b = 25   c = 26

Area: T = 243.7211152139
Perimeter: p = 72
Semiperimeter: s = 36

Angle ∠ A = α = 48.58326895819° = 48°34'58″ = 0.84879278927 rad
Angle ∠ B = β = 63.22110584075° = 63°13'16″ = 1.10334156258 rad
Angle ∠ C = γ = 68.19662520106° = 68°11'47″ = 1.19902491351 rad

Height: ha = 23.2121538299
Height: hb = 19.49876921711
Height: hc = 18.74877809338

Median: ma = 23.24332785983
Median: mb = 20.05661711201
Median: mc = 19.07987840283

Inradius: r = 6.77700320039
Circumradius: R = 14.00216570989

Vertex coordinates: A[26; 0] B[0; 0] C[9.46215384615; 18.74877809338]
Centroid: CG[11.82105128205; 6.24992603113]
Coordinates of the circumscribed circle: U[13; 5.20106154939]
Coordinates of the inscribed circle: I[11; 6.77700320039]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 131.4177310418° = 131°25'2″ = 0.84879278927 rad
∠ B' = β' = 116.7798941592° = 116°46'44″ = 1.10334156258 rad
∠ C' = γ' = 111.8043747989° = 111°48'13″ = 1.19902491351 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.