# 21 26 30 triangle

### Acute scalene triangle.

Sides: a = 21   b = 26   c = 30

Area: T = 267.55554849
Perimeter: p = 77
Semiperimeter: s = 38.5

Angle ∠ A = α = 43.31774289986° = 43°19'3″ = 0.75660317595 rad
Angle ∠ B = β = 58.1454569176° = 58°8'40″ = 1.01548141743 rad
Angle ∠ C = γ = 78.53880018254° = 78°32'17″ = 1.37107467198 rad

Height: ha = 25.48114747524
Height: hb = 20.58111911461
Height: hc = 17.83770323267

Median: ma = 26.03436320939
Median: mb = 22.39441956766
Median: mc = 18.26219823677

Inradius: r = 6.94994931143
Circumradius: R = 15.30552365999

Vertex coordinates: A[30; 0] B[0; 0] C[11.08333333333; 17.83770323267]
Centroid: CG[13.69444444444; 5.94656774422]
Coordinates of the circumscribed circle: U[15; 3.04114252218]
Coordinates of the inscribed circle: I[12.5; 6.94994931143]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 136.6832571001° = 136°40'57″ = 0.75660317595 rad
∠ B' = β' = 121.8555430824° = 121°51'20″ = 1.01548141743 rad
∠ C' = γ' = 101.4621998175° = 101°27'43″ = 1.37107467198 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.