# 15 21 27 triangle

### Obtuse scalene triangle.

Sides: a = 15   b = 21   c = 27

Area: T = 156.7110521344
Perimeter: p = 63
Semiperimeter: s = 31.5

Angle ∠ A = α = 33.55773097619° = 33°33'26″ = 0.58656855435 rad
Angle ∠ B = β = 50.70435197608° = 50°42'13″ = 0.88549433622 rad
Angle ∠ C = γ = 95.73991704773° = 95°44'21″ = 1.6710963748 rad

Height: ha = 20.89547361792
Height: hb = 14.92548115566
Height: hc = 11.60881867662

Median: ma = 22.99545645751
Median: mb = 19.15107180022
Median: mc = 12.27880291578

Inradius: r = 4.97549371855
Circumradius: R = 13.5688010506

Vertex coordinates: A[27; 0] B[0; 0] C[9.5; 11.60881867662]
Centroid: CG[12.16766666667; 3.86993955887]
Coordinates of the circumscribed circle: U[13.5; -1.35768010506]
Coordinates of the inscribed circle: I[10.5; 4.97549371855]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 146.4432690238° = 146°26'34″ = 0.58656855435 rad
∠ B' = β' = 129.2966480239° = 129°17'47″ = 0.88549433622 rad
∠ C' = γ' = 84.26108295227° = 84°15'39″ = 1.6710963748 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.