# 4 13 13 triangle

### Acute isosceles triangle.

Sides: a = 4   b = 13   c = 13

Area: T = 25.69904651573
Perimeter: p = 30
Semiperimeter: s = 15

Angle ∠ A = α = 17.76997661969° = 17°41'59″ = 0.3098919197 rad
Angle ∠ B = β = 81.15501169016° = 81°9' = 1.41663367283 rad
Angle ∠ C = γ = 81.15501169016° = 81°9' = 1.41663367283 rad

Height: ha = 12.84552325787
Height: hb = 3.9522379255
Height: hc = 3.9522379255

Median: ma = 12.84552325787
Median: mb = 7.08987234394
Median: mc = 7.08987234394

Inradius: r = 1.71326976772
Circumradius: R = 6.57883160782

Vertex coordinates: A[13; 0] B[0; 0] C[0.61553846154; 3.9522379255]
Centroid: CG[4.53884615385; 1.31774597517]
Coordinates of the circumscribed circle: U[6.5; 1.01220486274]
Coordinates of the inscribed circle: I[2; 1.71326976772]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 162.3300233803° = 162°18'1″ = 0.3098919197 rad
∠ B' = β' = 98.85498830984° = 98°51' = 1.41663367283 rad
∠ C' = γ' = 98.85498830984° = 98°51' = 1.41663367283 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.