# 14 18 21 triangle

### Acute scalene triangle.

Sides: a = 14   b = 18   c = 21

Area: T = 124.4432506805
Perimeter: p = 53
Semiperimeter: s = 26.5

Angle ∠ A = α = 41.18799379033° = 41°10'48″ = 0.71987255022 rad
Angle ∠ B = β = 57.83881365265° = 57°50'17″ = 1.00994659156 rad
Angle ∠ C = γ = 80.98219255702° = 80°58'55″ = 1.41334012358 rad

Height: ha = 17.77875009722
Height: hb = 13.82769452006
Height: hc = 11.85216673148

Median: ma = 18.26219823677
Median: mb = 15.41110350074
Median: mc = 12.23772382505

Inradius: r = 4.6965943653
Circumradius: R = 10.63114155345

Vertex coordinates: A[21; 0] B[0; 0] C[7.45223809524; 11.85216673148]
Centroid: CG[9.48441269841; 3.95105557716]
Coordinates of the circumscribed circle: U[10.5; 1.66664321969]
Coordinates of the inscribed circle: I[8.5; 4.6965943653]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 138.8220062097° = 138°49'12″ = 0.71987255022 rad
∠ B' = β' = 122.1621863473° = 122°9'43″ = 1.00994659156 rad
∠ C' = γ' = 99.01880744298° = 99°1'5″ = 1.41334012358 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.