# 9 28 28 triangle

### Acute isosceles triangle.

Sides: a = 9   b = 28   c = 28

Area: T = 124.3622122449
Perimeter: p = 65
Semiperimeter: s = 32.5

Angle ∠ A = α = 18.49767166758° = 18°29'48″ = 0.32328286068 rad
Angle ∠ B = β = 80.75216416621° = 80°45'6″ = 1.40993820234 rad
Angle ∠ C = γ = 80.75216416621° = 80°45'6″ = 1.40993820234 rad

Height: ha = 27.63660272109
Height: hb = 8.88330087464
Height: hc = 8.88330087464

Median: ma = 27.63660272109
Median: mb = 15.37985564992
Median: mc = 15.37985564992

Inradius: r = 3.82765268446
Circumradius: R = 14.18443831969

Vertex coordinates: A[28; 0] B[0; 0] C[1.44664285714; 8.88330087464]
Centroid: CG[9.81554761905; 2.96110029155]
Coordinates of the circumscribed circle: U[14; 2.28796330138]
Coordinates of the inscribed circle: I[4.5; 3.82765268446]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 161.5033283324° = 161°30'12″ = 0.32328286068 rad
∠ B' = β' = 99.24883583379° = 99°14'54″ = 1.40993820234 rad
∠ C' = γ' = 99.24883583379° = 99°14'54″ = 1.40993820234 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.