# 4 8 8 triangle

### Acute isosceles triangle.

Sides: a = 4   b = 8   c = 8

Area: T = 15.49219333848
Perimeter: p = 20
Semiperimeter: s = 10

Angle ∠ A = α = 28.95550243719° = 28°57'18″ = 0.50553605103 rad
Angle ∠ B = β = 75.52224878141° = 75°31'21″ = 1.31881160717 rad
Angle ∠ C = γ = 75.52224878141° = 75°31'21″ = 1.31881160717 rad

Height: ha = 7.74659666924
Height: hb = 3.87329833462
Height: hc = 3.87329833462

Median: ma = 7.74659666924
Median: mb = 4.89989794856
Median: mc = 4.89989794856

Inradius: r = 1.54991933385
Circumradius: R = 4.1311182236

Vertex coordinates: A[8; 0] B[0; 0] C[1; 3.87329833462]
Centroid: CG[3; 1.29109944487]
Coordinates of the circumscribed circle: U[4; 1.0332795559]
Coordinates of the inscribed circle: I[2; 1.54991933385]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.0454975628° = 151°2'42″ = 0.50553605103 rad
∠ B' = β' = 104.4787512186° = 104°28'39″ = 1.31881160717 rad
∠ C' = γ' = 104.4787512186° = 104°28'39″ = 1.31881160717 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    