# 21 21 29 triangle

### Acute isosceles triangle.

Sides: a = 21   b = 21   c = 29

Area: T = 220.2621634199
Perimeter: p = 71
Semiperimeter: s = 35.5

Angle ∠ A = α = 46.33221847017° = 46°19'56″ = 0.80986491727 rad
Angle ∠ B = β = 46.33221847017° = 46°19'56″ = 0.80986491727 rad
Angle ∠ C = γ = 87.33656305966° = 87°20'8″ = 1.52442943082 rad

Height: ha = 20.97772984951
Height: hb = 20.97772984951
Height: hc = 15.1990457531

Median: ma = 23.0388012067
Median: mb = 23.0388012067
Median: mc = 15.1990457531

Inradius: r = 6.2054553076
Circumradius: R = 14.51656918118

Vertex coordinates: A[29; 0] B[0; 0] C[14.5; 15.1990457531]
Centroid: CG[14.5; 5.06334858437]
Coordinates of the circumscribed circle: U[14.5; 0.67547657191]
Coordinates of the inscribed circle: I[14.5; 6.2054553076]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 133.6687815298° = 133°40'4″ = 0.80986491727 rad
∠ B' = β' = 133.6687815298° = 133°40'4″ = 0.80986491727 rad
∠ C' = γ' = 92.66443694034° = 92°39'52″ = 1.52442943082 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.