# 15 28 28 triangle

### Acute isosceles triangle.

Sides: a = 15   b = 28   c = 28

Area: T = 202.3266314403
Perimeter: p = 71
Semiperimeter: s = 35.5

Angle ∠ A = α = 31.07435881363° = 31°4'25″ = 0.54223364234 rad
Angle ∠ B = β = 74.46332059318° = 74°27'48″ = 1.32996281151 rad
Angle ∠ C = γ = 74.46332059318° = 74°27'48″ = 1.32996281151 rad

Height: ha = 26.97768419204
Height: hb = 14.45218796002
Height: hc = 14.45218796002

Median: ma = 26.97768419204
Median: mb = 17.56441680703
Median: mc = 17.56441680703

Inradius: r = 5.69993328001
Circumradius: R = 14.53109818383

Vertex coordinates: A[28; 0] B[0; 0] C[4.01878571429; 14.45218796002]
Centroid: CG[10.67326190476; 4.81772932001]
Coordinates of the circumscribed circle: U[14; 3.89222272781]
Coordinates of the inscribed circle: I[7.5; 5.69993328001]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.9266411864° = 148°55'35″ = 0.54223364234 rad
∠ B' = β' = 105.5376794068° = 105°32'12″ = 1.32996281151 rad
∠ C' = γ' = 105.5376794068° = 105°32'12″ = 1.32996281151 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.