# 21 26 26 triangle

### Acute isosceles triangle.

Sides: a = 21   b = 26   c = 26

Area: T = 249.7487747738
Perimeter: p = 73
Semiperimeter: s = 36.5

Angle ∠ A = α = 47.63876827869° = 47°38'16″ = 0.83114344127 rad
Angle ∠ B = β = 66.18111586065° = 66°10'52″ = 1.15550791205 rad
Angle ∠ C = γ = 66.18111586065° = 66°10'52″ = 1.15550791205 rad

Height: ha = 23.78554997845
Height: hb = 19.21113652106
Height: hc = 19.21113652106

Median: ma = 23.78554997845
Median: mb = 19.7365754356
Median: mc = 19.7365754356

Inradius: r = 6.84224040476
Circumradius: R = 14.211033836

Vertex coordinates: A[26; 0] B[0; 0] C[8.48107692308; 19.21113652106]
Centroid: CG[11.49435897436; 6.40437884035]
Coordinates of the circumscribed circle: U[13; 5.73987904915]
Coordinates of the inscribed circle: I[10.5; 6.84224040476]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 132.3622317213° = 132°21'44″ = 0.83114344127 rad
∠ B' = β' = 113.8198841393° = 113°49'8″ = 1.15550791205 rad
∠ C' = γ' = 113.8198841393° = 113°49'8″ = 1.15550791205 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.