# 1 18 18 triangle

### Acute isosceles triangle.

Sides: a = 1   b = 18   c = 18

Area: T = 8.99765271077
Perimeter: p = 37
Semiperimeter: s = 18.5

Angle ∠ A = α = 3.18435083532° = 3°11'1″ = 0.05655627025 rad
Angle ∠ B = β = 88.40882458234° = 88°24'30″ = 1.54330149755 rad
Angle ∠ C = γ = 88.40882458234° = 88°24'30″ = 1.54330149755 rad

Height: ha = 17.99330542154
Height: hb = 10.9996141231
Height: hc = 10.9996141231

Median: ma = 17.99330542154
Median: mb = 9.02877350426
Median: mc = 9.02877350426

Inradius: r = 0.48662987626
Circumradius: R = 9.00334742329

Vertex coordinates: A[18; 0] B[0; 0] C[0.02877777778; 10.9996141231]
Centroid: CG[6.00992592593; 0.33332047077]
Coordinates of the circumscribed circle: U[9; 0.25500965065]
Coordinates of the inscribed circle: I[0.5; 0.48662987626]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 176.8166491647° = 176°48'59″ = 0.05655627025 rad
∠ B' = β' = 91.59217541766° = 91°35'30″ = 1.54330149755 rad
∠ C' = γ' = 91.59217541766° = 91°35'30″ = 1.54330149755 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.