# 7 8 12 triangle

### Obtuse scalene triangle.

Sides: a = 7   b = 8   c = 12

Area: T = 26.9066086672
Perimeter: p = 27
Semiperimeter: s = 13.5

Angle ∠ A = α = 34.09333908114° = 34°5'36″ = 0.59550419228 rad
Angle ∠ B = β = 39.83881498056° = 39°50'17″ = 0.6955306882 rad
Angle ∠ C = γ = 106.0688459383° = 106°4'6″ = 1.85112438488 rad

Height: ha = 7.68774533349
Height: hb = 6.7276521668
Height: hc = 4.48443477787

Median: ma = 9.57986220303
Median: mb = 8.97221792225
Median: mc = 4.52876925691

Inradius: r = 1.99330434572
Circumradius: R = 6.24439403414

Vertex coordinates: A[12; 0] B[0; 0] C[5.375; 4.48443477787]
Centroid: CG[5.79216666667; 1.49547825929]
Coordinates of the circumscribed circle: U[6; -1.72882334873]
Coordinates of the inscribed circle: I[5.5; 1.99330434572]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 145.9076609189° = 145°54'24″ = 0.59550419228 rad
∠ B' = β' = 140.1621850194° = 140°9'43″ = 0.6955306882 rad
∠ C' = γ' = 73.9321540617° = 73°55'54″ = 1.85112438488 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.