# 5 16 18 triangle

### Obtuse scalene triangle.

Sides: a = 5   b = 16   c = 18

Area: T = 38.52883986171
Perimeter: p = 39
Semiperimeter: s = 19.5

Angle ∠ A = α = 15.51990244034° = 15°31'8″ = 0.27108580725 rad
Angle ∠ B = β = 58.89110774895° = 58°53'28″ = 1.02878432022 rad
Angle ∠ C = γ = 105.5989898107° = 105°35'24″ = 1.84328913788 rad

Height: ha = 15.41113594468
Height: hb = 4.81660498271
Height: hc = 4.28109331797

Median: ma = 16.84548805279
Median: mb = 10.51218980208
Median: mc = 7.71436243103

Inradius: r = 1.97658153137
Circumradius: R = 9.34437571485

Vertex coordinates: A[18; 0] B[0; 0] C[2.58333333333; 4.28109331797]
Centroid: CG[6.86111111111; 1.42769777266]
Coordinates of the circumscribed circle: U[9; -2.51111347337]
Coordinates of the inscribed circle: I[3.5; 1.97658153137]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 164.4810975597° = 164°28'52″ = 0.27108580725 rad
∠ B' = β' = 121.1098922511° = 121°6'32″ = 1.02878432022 rad
∠ C' = γ' = 74.41101018929° = 74°24'36″ = 1.84328913788 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.