# 13 15 18 triangle

### Acute scalene triangle.

Sides: a = 13   b = 15   c = 18

Area: T = 95.91766304663
Perimeter: p = 46
Semiperimeter: s = 23

Angle ∠ A = α = 45.27550868451° = 45°16'30″ = 0.79901993346 rad
Angle ∠ B = β = 55.06548040489° = 55°3'53″ = 0.96110621326 rad
Angle ∠ C = γ = 79.66601091061° = 79°39'36″ = 1.39903311864 rad

Height: ha = 14.75664046871
Height: hb = 12.78988840622
Height: hc = 10.65774033851

Median: ma = 15.24397506541
Median: mb = 13.79331142241
Median: mc = 10.77703296143

Inradius: r = 4.17702882811
Circumradius: R = 9.14985699168

Vertex coordinates: A[18; 0] B[0; 0] C[7.44444444444; 10.65774033851]
Centroid: CG[8.48114814815; 3.5522467795]
Coordinates of the circumscribed circle: U[9; 1.64220510107]
Coordinates of the inscribed circle: I[8; 4.17702882811]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 134.7254913155° = 134°43'30″ = 0.79901993346 rad
∠ B' = β' = 124.9355195951° = 124°56'7″ = 0.96110621326 rad
∠ C' = γ' = 100.3439890894° = 100°20'24″ = 1.39903311864 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.