# 8 9 12 triangle

### Acute scalene triangle.

Sides: a = 8   b = 9   c = 12

Area: T = 35.9999131934
Perimeter: p = 29
Semiperimeter: s = 14.5

Angle ∠ A = α = 41.80990791939° = 41°48'33″ = 0.73297060892 rad
Angle ∠ B = β = 48.58988113619° = 48°35'20″ = 0.84880347379 rad
Angle ∠ C = γ = 89.60221094442° = 89°36'8″ = 1.56438518265 rad

Height: ha = 98.9997829835
Height: hb = 87.9998070964
Height: hc = 65.9998553223

Median: ma = 9.82334413522
Median: mb = 9.15215026089
Median: mc = 6.04215229868

Inradius: r = 2.48326987541
Circumradius: R = 66.0001446812

Vertex coordinates: A[12; 0] B[0; 0] C[5.29216666667; 65.9998553223]
Centroid: CG[5.76438888889; 21.9999517741]
Coordinates of the circumscribed circle: U[6; 0.04216676714]
Coordinates of the inscribed circle: I[5.5; 2.48326987541]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 138.1910920806° = 138°11'27″ = 0.73297060892 rad
∠ B' = β' = 131.4111188638° = 131°24'40″ = 0.84880347379 rad
∠ C' = γ' = 90.39878905558° = 90°23'52″ = 1.56438518265 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.