# 15 23 26 triangle

### Acute scalene triangle.

Sides: a = 15   b = 23   c = 26

Area: T = 171.3944282285
Perimeter: p = 64
Semiperimeter: s = 32

Angle ∠ A = α = 34.9755424097° = 34°58'32″ = 0.61104363078 rad
Angle ∠ B = β = 61.51553646048° = 61°30'55″ = 1.07436456529 rad
Angle ∠ C = γ = 83.50992112982° = 83°30'33″ = 1.45875106929 rad

Height: ha = 22.85325709713
Height: hb = 14.90438506335
Height: hc = 13.18441755604

Median: ma = 23.3721991785
Median: mb = 17.84395627749
Median: mc = 14.42222051019

Inradius: r = 5.35660713214
Circumradius: R = 13.08438670351

Vertex coordinates: A[26; 0] B[0; 0] C[7.15438461538; 13.18441755604]
Centroid: CG[11.05112820513; 4.39547251868]
Coordinates of the circumscribed circle: U[13; 1.47990458388]
Coordinates of the inscribed circle: I[9; 5.35660713214]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 145.0254575903° = 145°1'28″ = 0.61104363078 rad
∠ B' = β' = 118.4854635395° = 118°29'5″ = 1.07436456529 rad
∠ C' = γ' = 96.49107887018° = 96°29'27″ = 1.45875106929 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    