# 18 18 25 triangle

### Acute isosceles triangle.

Sides: a = 18   b = 18   c = 25

Area: T = 161.8987923087
Perimeter: p = 61
Semiperimeter: s = 30.5

Angle ∠ A = α = 46.01770368696° = 46°1'1″ = 0.80331488054 rad
Angle ∠ B = β = 46.01770368696° = 46°1'1″ = 0.80331488054 rad
Angle ∠ C = γ = 87.96659262607° = 87°57'57″ = 1.53552950428 rad

Height: ha = 17.98986581208
Height: hb = 17.98986581208
Height: hc = 12.9521833847

Median: ma = 19.83768344249
Median: mb = 19.83768344249
Median: mc = 12.9521833847

Inradius: r = 5.30881286258
Circumradius: R = 12.5087881271

Vertex coordinates: A[25; 0] B[0; 0] C[12.5; 12.9521833847]
Centroid: CG[12.5; 4.3177277949]
Coordinates of the circumscribed circle: U[12.5; 0.4443952576]
Coordinates of the inscribed circle: I[12.5; 5.30881286258]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.983296313° = 133°58'59″ = 0.80331488054 rad
∠ B' = β' = 133.983296313° = 133°58'59″ = 0.80331488054 rad
∠ C' = γ' = 92.03440737393° = 92°2'3″ = 1.53552950428 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.