# 6 7 7 triangle

### Acute isosceles triangle.

Sides: a = 6   b = 7   c = 7

Area: T = 18.9743665961
Perimeter: p = 20
Semiperimeter: s = 10

Angle ∠ A = α = 50.75438670503° = 50°45'14″ = 0.88658220881 rad
Angle ∠ B = β = 64.62330664748° = 64°37'23″ = 1.12878852827 rad
Angle ∠ C = γ = 64.62330664748° = 64°37'23″ = 1.12878852827 rad

Height: ha = 6.32545553203
Height: hb = 5.42110474174
Height: hc = 5.42110474174

Median: ma = 6.32545553203
Median: mb = 5.5
Median: mc = 5.5

Inradius: r = 1.89773665961
Circumradius: R = 3.87437901337

Vertex coordinates: A[7; 0] B[0; 0] C[2.57114285714; 5.42110474174]
Centroid: CG[3.19904761905; 1.80770158058]
Coordinates of the circumscribed circle: U[3.5; 1.66601957716]
Coordinates of the inscribed circle: I[3; 1.89773665961]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 129.246613295° = 129°14'46″ = 0.88658220881 rad
∠ B' = β' = 115.3776933525° = 115°22'37″ = 1.12878852827 rad
∠ C' = γ' = 115.3776933525° = 115°22'37″ = 1.12878852827 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    