# 18 22 30 triangle

### Obtuse scalene triangle.

Sides: a = 18   b = 22   c = 30

Area: T = 196.6659604393
Perimeter: p = 70
Semiperimeter: s = 35

Angle ∠ A = α = 36.58795428375° = 36°34'46″ = 0.63884334614 rad
Angle ∠ B = β = 46.75498273458° = 46°44'59″ = 0.81659384119 rad
Angle ∠ C = γ = 96.67106298167° = 96°40'14″ = 1.68772207803 rad

Height: ha = 21.85110671548
Height: hb = 17.87881458539
Height: hc = 13.11106402929

Median: ma = 24.71884141886
Median: mb = 22.15985198062
Median: mc = 13.37990881603

Inradius: r = 5.61988458398
Circumradius: R = 15.10222372346

Vertex coordinates: A[30; 0] B[0; 0] C[12.33333333333; 13.11106402929]
Centroid: CG[14.11111111111; 4.3770213431]
Coordinates of the circumscribed circle: U[15; -1.75443002848]
Coordinates of the inscribed circle: I[13; 5.61988458398]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 143.4220457162° = 143°25'14″ = 0.63884334614 rad
∠ B' = β' = 133.2550172654° = 133°15'1″ = 0.81659384119 rad
∠ C' = γ' = 83.32993701833° = 83°19'46″ = 1.68772207803 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    