# 12.7 9.9 9.31 triangle

### Acute scalene triangle.

Sides: a = 12.7   b = 9.9   c = 9.31

Area: T = 45.71218151773
Perimeter: p = 31.91
Semiperimeter: s = 15.955

Angle ∠ A = α = 82.7088377834° = 82°42'30″ = 1.44435335122 rad
Angle ∠ B = β = 50.64442480173° = 50°38'39″ = 0.88439088751 rad
Angle ∠ C = γ = 46.64773741486° = 46°38'51″ = 0.81441502663 rad

Height: ha = 7.19987110515
Height: hb = 9.23547101368
Height: hc = 9.82199388136

Median: ma = 7.21325272963
Median: mb = 9.97439936836
Median: mc = 10.39113894644

Inradius: r = 2.86550463916
Circumradius: R = 6.4021771049

Vertex coordinates: A[9.31; 0] B[0; 0] C[8.05334962406; 9.82199388136]
Centroid: CG[5.78878320802; 3.27333129379]
Coordinates of the circumscribed circle: U[4.655; 4.39547295212]
Coordinates of the inscribed circle: I[6.055; 2.86550463916]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 97.2921622166° = 97°17'30″ = 1.44435335122 rad
∠ B' = β' = 129.3565751983° = 129°21'21″ = 0.88439088751 rad
∠ C' = γ' = 133.3532625851° = 133°21'9″ = 0.81441502663 rad

# How did we calculate this triangle?

### 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    