# 18 18 22 triangle

### Acute isosceles triangle.

Sides: a = 18   b = 18   c = 22

Area: T = 156.7265875336
Perimeter: p = 58
Semiperimeter: s = 29

Angle ∠ A = α = 52.33301130357° = 52°19'48″ = 0.91333327704 rad
Angle ∠ B = β = 52.33301130357° = 52°19'48″ = 0.91333327704 rad
Angle ∠ C = γ = 75.34397739287° = 75°20'23″ = 1.31549271128 rad

Height: ha = 17.41439861485
Height: hb = 17.41439861485
Height: hc = 14.24878068488

Median: ma = 17.97222007556
Median: mb = 17.97222007556
Median: mc = 14.24878068488

Inradius: r = 5.40443405288
Circumradius: R = 11.37701709828

Vertex coordinates: A[22; 0] B[0; 0] C[11; 14.24878068488]
Centroid: CG[11; 4.74992689496]
Coordinates of the circumscribed circle: U[11; 2.8787635866]
Coordinates of the inscribed circle: I[11; 5.40443405288]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 127.6769886964° = 127°40'12″ = 0.91333327704 rad
∠ B' = β' = 127.6769886964° = 127°40'12″ = 0.91333327704 rad
∠ C' = γ' = 104.6660226071° = 104°39'37″ = 1.31549271128 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    