# 5 15 18 triangle

### Obtuse scalene triangle.

Sides: a = 5   b = 15   c = 18

Area: T = 32.61990128606
Perimeter: p = 38
Semiperimeter: s = 19

Angle ∠ A = α = 13.98223106495° = 13°58'56″ = 0.24440373579 rad
Angle ∠ B = β = 46.45877809718° = 46°27'28″ = 0.81108412411 rad
Angle ∠ C = γ = 119.5659908379° = 119°33'36″ = 2.08767140546 rad

Height: ha = 13.04876051442
Height: hb = 4.34992017147
Height: hc = 3.62443347623

Median: ma = 16.37883393542
Median: mb = 10.87442815855
Median: mc = 6.63332495807

Inradius: r = 1.71767901506
Circumradius: R = 10.34767263538

Vertex coordinates: A[18; 0] B[0; 0] C[3.44444444444; 3.62443347623]
Centroid: CG[7.14881481481; 1.20881115874]
Coordinates of the circumscribed circle: U[9; -5.10443850012]
Coordinates of the inscribed circle: I[4; 1.71767901506]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 166.0187689351° = 166°1'4″ = 0.24440373579 rad
∠ B' = β' = 133.5422219028° = 133°32'32″ = 0.81108412411 rad
∠ C' = γ' = 60.44400916213° = 60°26'24″ = 2.08767140546 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.