# 18 18 29 triangle

### Obtuse isosceles triangle.

Sides: a = 18   b = 18   c = 29

Area: T = 154.6487785306
Perimeter: p = 65
Semiperimeter: s = 32.5

Angle ∠ A = α = 36.33660575146° = 36°20'10″ = 0.63441838408 rad
Angle ∠ B = β = 36.33660575146° = 36°20'10″ = 0.63441838408 rad
Angle ∠ C = γ = 107.3287884971° = 107°19'40″ = 1.87332249719 rad

Height: ha = 17.18330872562
Height: hb = 17.18330872562
Height: hc = 10.66553645039

Median: ma = 22.39441956766
Median: mb = 22.39441956766
Median: mc = 10.66553645039

Inradius: r = 4.7588393394
Circumradius: R = 15.18993542824

Vertex coordinates: A[29; 0] B[0; 0] C[14.5; 10.66553645039]
Centroid: CG[14.5; 3.55551215013]
Coordinates of the circumscribed circle: U[14.5; -4.52439897786]
Coordinates of the inscribed circle: I[14.5; 4.7588393394]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 143.6643942485° = 143°39'50″ = 0.63441838408 rad
∠ B' = β' = 143.6643942485° = 143°39'50″ = 0.63441838408 rad
∠ C' = γ' = 72.67221150292° = 72°40'20″ = 1.87332249719 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.