# 18 18 23 triangle

### Acute isosceles triangle.

Sides: a = 18   b = 18   c = 23

Area: T = 159.2454897877
Perimeter: p = 59
Semiperimeter: s = 29.5

Angle ∠ A = α = 50.29109834469° = 50°17'28″ = 0.87877432452 rad
Angle ∠ B = β = 50.29109834469° = 50°17'28″ = 0.87877432452 rad
Angle ∠ C = γ = 79.41880331061° = 79°25'5″ = 1.38661061632 rad

Height: ha = 17.69438775419
Height: hb = 17.69438775419
Height: hc = 13.84773824241

Median: ma = 18.58876302954
Median: mb = 18.58876302954
Median: mc = 13.84773824241

Inradius: r = 5.39881321314
Circumradius: R = 11.69989619437

Vertex coordinates: A[23; 0] B[0; 0] C[11.5; 13.84773824241]
Centroid: CG[11.5; 4.61657941414]
Coordinates of the circumscribed circle: U[11.5; 2.14884204804]
Coordinates of the inscribed circle: I[11.5; 5.39881321314]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 129.7099016553° = 129°42'32″ = 0.87877432452 rad
∠ B' = β' = 129.7099016553° = 129°42'32″ = 0.87877432452 rad
∠ C' = γ' = 100.5821966894° = 100°34'55″ = 1.38661061632 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.