# 6 13 18 triangle

### Obtuse scalene triangle.

Sides: a = 6   b = 13   c = 18

Area: T = 25.21878012523
Perimeter: p = 37
Semiperimeter: s = 18.5

Angle ∠ A = α = 12.44770198968° = 12°26'49″ = 0.21772414793 rad
Angle ∠ B = β = 27.83994971122° = 27°50'22″ = 0.48658908867 rad
Angle ∠ C = γ = 139.7133482991° = 139°42'49″ = 2.43884602876 rad

Height: ha = 8.40659337508
Height: hb = 3.88796617311
Height: hc = 2.80219779169

Median: ma = 15.41110350074
Median: mb = 11.73766945943
Median: mc = 4.63768092477

Inradius: r = 1.3633124392
Circumradius: R = 13.91987392465

Vertex coordinates: A[18; 0] B[0; 0] C[5.30655555556; 2.80219779169]
Centroid: CG[7.76985185185; 0.9343992639]
Coordinates of the circumscribed circle: U[9; -10.61774998098]
Coordinates of the inscribed circle: I[5.5; 1.3633124392]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.5532980103° = 167°33'11″ = 0.21772414793 rad
∠ B' = β' = 152.1610502888° = 152°9'38″ = 0.48658908867 rad
∠ C' = γ' = 40.2876517009° = 40°17'11″ = 2.43884602876 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.