# 8 18 18 triangle

### Acute isosceles triangle.

Sides: a = 8   b = 18   c = 18

Area: T = 70.21997150991
Perimeter: p = 44
Semiperimeter: s = 22

Angle ∠ A = α = 25.67991768138° = 25°40'45″ = 0.44881861846 rad
Angle ∠ B = β = 77.16604115931° = 77°9'37″ = 1.34767032345 rad
Angle ∠ C = γ = 77.16604115931° = 77°9'37″ = 1.34767032345 rad

Height: ha = 17.55499287748
Height: hb = 7.87999683443
Height: hc = 7.87999683443

Median: ma = 17.55499287748
Median: mb = 10.63301458127
Median: mc = 10.63301458127

Inradius: r = 3.19108961409
Circumradius: R = 9.23108066932

Vertex coordinates: A[18; 0] B[0; 0] C[1.77877777778; 7.87999683443]
Centroid: CG[6.59325925926; 2.65999894481]
Coordinates of the circumscribed circle: U[9; 2.05112903763]
Coordinates of the inscribed circle: I[4; 3.19108961409]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 154.3210823186° = 154°19'15″ = 0.44881861846 rad
∠ B' = β' = 102.8439588407° = 102°50'23″ = 1.34767032345 rad
∠ C' = γ' = 102.8439588407° = 102°50'23″ = 1.34767032345 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.