# 9 13 13 triangle

### Acute isosceles triangle.

Sides: a = 9   b = 13   c = 13

Area: T = 54.88333991294
Perimeter: p = 35
Semiperimeter: s = 17.5

Angle ∠ A = α = 40.50444934844° = 40°30'16″ = 0.70769367732 rad
Angle ∠ B = β = 69.74877532578° = 69°44'52″ = 1.21773279402 rad
Angle ∠ C = γ = 69.74877532578° = 69°44'52″ = 1.21773279402 rad

Height: ha = 12.19663109177
Height: hb = 8.44435998661
Height: hc = 8.44435998661

Median: ma = 12.19663109177
Median: mb = 9.09767026993
Median: mc = 9.09767026993

Inradius: r = 3.1366194236
Circumradius: R = 6.92883245213

Vertex coordinates: A[13; 0] B[0; 0] C[3.11553846154; 8.44435998661]
Centroid: CG[5.37217948718; 2.81545332887]
Coordinates of the circumscribed circle: U[6.5; 2.39882661804]
Coordinates of the inscribed circle: I[4.5; 3.1366194236]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 139.4965506516° = 139°29'44″ = 0.70769367732 rad
∠ B' = β' = 110.2522246742° = 110°15'8″ = 1.21773279402 rad
∠ C' = γ' = 110.2522246742° = 110°15'8″ = 1.21773279402 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.