# 17 18 18 triangle

### Acute isosceles triangle.

Sides: a = 17   b = 18   c = 18

Area: T = 134.8666369047
Perimeter: p = 53
Semiperimeter: s = 26.5

Angle ∠ A = α = 56.35772854811° = 56°21'26″ = 0.98436201891 rad
Angle ∠ B = β = 61.82113572595° = 61°49'17″ = 1.07989862322 rad
Angle ∠ C = γ = 61.82113572595° = 61°49'17″ = 1.07989862322 rad

Height: ha = 15.86766316526
Height: hb = 14.98551521164
Height: hc = 14.98551521164

Median: ma = 15.86766316526
Median: mb = 15.01766574177
Median: mc = 15.01766574177

Inradius: r = 5.08992969452
Circumradius: R = 10.21101065649

Vertex coordinates: A[18; 0] B[0; 0] C[8.02877777778; 14.98551521164]
Centroid: CG[8.67659259259; 4.99550507055]
Coordinates of the circumscribed circle: U[9; 4.82114392112]
Coordinates of the inscribed circle: I[8.5; 5.08992969452]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 123.6432714519° = 123°38'34″ = 0.98436201891 rad
∠ B' = β' = 118.1798642741° = 118°10'43″ = 1.07989862322 rad
∠ C' = γ' = 118.1798642741° = 118°10'43″ = 1.07989862322 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.