# 12 17 28 triangle

### Obtuse scalene triangle.

Sides: a = 12   b = 17   c = 28

Area: T = 51.9999399035
Perimeter: p = 57
Semiperimeter: s = 28.5

Angle ∠ A = α = 12.62200576915° = 12°37'12″ = 0.22202615585 rad
Angle ∠ B = β = 18.03303198517° = 18°1'49″ = 0.31546884466 rad
Angle ∠ C = γ = 149.3549622457° = 149°20'59″ = 2.60766426485 rad

Height: ha = 8.66765665058
Height: hb = 6.11875763571
Height: hc = 3.71442427882

Median: ma = 22.37218573212
Median: mb = 19.79326754129
Median: mc = 4.52876925691

Inradius: r = 1.8254540317
Circumradius: R = 27.46218558387

Vertex coordinates: A[28; 0] B[0; 0] C[11.41107142857; 3.71442427882]
Centroid: CG[13.13769047619; 1.23880809294]
Coordinates of the circumscribed circle: U[14; -23.62552730377]
Coordinates of the inscribed circle: I[11.5; 1.8254540317]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 167.3879942308° = 167°22'48″ = 0.22202615585 rad
∠ B' = β' = 161.9769680148° = 161°58'11″ = 0.31546884466 rad
∠ C' = γ' = 30.65503775432° = 30°39'1″ = 2.60766426485 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.