# 15 15 26 triangle

### Obtuse isosceles triangle.

Sides: a = 15   b = 15   c = 26

Area: T = 97.28330920561
Perimeter: p = 56
Semiperimeter: s = 28

Angle ∠ A = α = 29.92664348666° = 29°55'35″ = 0.52223148218 rad
Angle ∠ B = β = 29.92664348666° = 29°55'35″ = 0.52223148218 rad
Angle ∠ C = γ = 120.1477130267° = 120°8'50″ = 2.097696301 rad

Height: ha = 12.97110789408
Height: hb = 12.97110789408
Height: hc = 7.48333147735

Median: ma = 19.85657296517
Median: mb = 19.85657296517
Median: mc = 7.48333147735

Inradius: r = 3.47443961449
Circumradius: R = 15.03334448576

Vertex coordinates: A[26; 0] B[0; 0] C[13; 7.48333147735]
Centroid: CG[13; 2.49444382578]
Coordinates of the circumscribed circle: U[13; -7.5550130084]
Coordinates of the inscribed circle: I[13; 3.47443961449]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 150.0743565133° = 150°4'25″ = 0.52223148218 rad
∠ B' = β' = 150.0743565133° = 150°4'25″ = 0.52223148218 rad
∠ C' = γ' = 59.85328697332° = 59°51'10″ = 2.097696301 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.