# 25 25 28 triangle

### Acute isosceles triangle.

Sides: a = 25   b = 25   c = 28

Area: T = 289.9722412481
Perimeter: p = 78
Semiperimeter: s = 39

Angle ∠ A = α = 55.94442022574° = 55°56'39″ = 0.97664105268 rad
Angle ∠ B = β = 55.94442022574° = 55°56'39″ = 0.97664105268 rad
Angle ∠ C = γ = 68.11215954851° = 68°6'42″ = 1.18987716 rad

Height: ha = 23.19877929985
Height: hb = 23.19877929985
Height: hc = 20.71223151772

Median: ma = 23.41547389479
Median: mb = 23.41547389479
Median: mc = 20.71223151772

Inradius: r = 7.43551900636
Circumradius: R = 15.08876421745

Vertex coordinates: A[28; 0] B[0; 0] C[14; 20.71223151772]
Centroid: CG[14; 6.90441050591]
Coordinates of the circumscribed circle: U[14; 5.62546730027]
Coordinates of the inscribed circle: I[14; 7.43551900636]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 124.0565797743° = 124°3'21″ = 0.97664105268 rad
∠ B' = β' = 124.0565797743° = 124°3'21″ = 0.97664105268 rad
∠ C' = γ' = 111.8888404515° = 111°53'18″ = 1.18987716 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.