# 4 16 18 triangle

### Obtuse scalene triangle.

Sides: a = 4   b = 16   c = 18

Area: T = 29.24403830344
Perimeter: p = 38
Semiperimeter: s = 19

Angle ∠ A = α = 11.71658523949° = 11°42'57″ = 0.2044480199 rad
Angle ∠ B = β = 54.31546652873° = 54°18'53″ = 0.94879697414 rad
Angle ∠ C = γ = 113.9699482318° = 113°58'10″ = 1.98991427132 rad

Height: ha = 14.62201915172
Height: hb = 3.65550478793
Height: hc = 3.24989314483

Median: ma = 16.91215345253
Median: mb = 10.2965630141
Median: mc = 7.41661984871

Inradius: r = 1.53989675281
Circumradius: R = 9.849939218

Vertex coordinates: A[18; 0] B[0; 0] C[2.33333333333; 3.24989314483]
Centroid: CG[6.77877777778; 1.08329771494]
Coordinates of the circumscribed circle: U[9; -4.00113155731]
Coordinates of the inscribed circle: I[3; 1.53989675281]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 168.2844147605° = 168°17'3″ = 0.2044480199 rad
∠ B' = β' = 125.6855334713° = 125°41'7″ = 0.94879697414 rad
∠ C' = γ' = 66.03105176822° = 66°1'50″ = 1.98991427132 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.