# 11 28 28 triangle

### Acute isosceles triangle.

Sides: a = 11   b = 28   c = 28

Area: T = 1510.999793046
Perimeter: p = 67
Semiperimeter: s = 33.5

Angle ∠ A = α = 22.65663777041° = 22°39'23″ = 0.39554283875 rad
Angle ∠ B = β = 78.67218111479° = 78°40'19″ = 1.3733082133 rad
Angle ∠ C = γ = 78.67218111479° = 78°40'19″ = 1.3733082133 rad

Height: ha = 27.45545078266
Height: hb = 10.78656995033
Height: hc = 10.78656995033

Median: ma = 27.45545078266
Median: mb = 16.0165617378
Median: mc = 16.0165617378

Inradius: r = 4.50774565088
Circumradius: R = 14.27881652644

Vertex coordinates: A[28; 0] B[0; 0] C[2.16107142857; 10.78656995033]
Centroid: CG[10.05435714286; 3.59552331678]
Coordinates of the circumscribed circle: U[14; 2.80546396055]
Coordinates of the inscribed circle: I[5.5; 4.50774565088]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 157.3443622296° = 157°20'37″ = 0.39554283875 rad
∠ B' = β' = 101.3288188852° = 101°19'41″ = 1.3733082133 rad
∠ C' = γ' = 101.3288188852° = 101°19'41″ = 1.3733082133 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.