2 3 4 triangle

Obtuse scalene triangle.

Sides: a = 2   b = 3   c = 4

Area: T = 2.90547375097
Perimeter: p = 9
Semiperimeter: s = 4.5

Angle ∠ A = α = 28.95550243719° = 28°57'18″ = 0.50553605103 rad
Angle ∠ B = β = 46.56774634422° = 46°34'3″ = 0.81327555614 rad
Angle ∠ C = γ = 104.4787512186° = 104°28'39″ = 1.82334765819 rad

Height: ha = 2.90547375097
Height: hb = 1.93664916731
Height: hc = 1.45223687548

Median: ma = 3.39111649916
Median: mb = 2.78438821814
Median: mc = 1.58111388301

Inradius: r = 0.64554972244
Circumradius: R = 2.0665591118

Vertex coordinates: A[4; 0] B[0; 0] C[1.375; 1.45223687548]
Centroid: CG[1.79216666667; 0.48441229183]
Coordinates of the circumscribed circle: U[2; -0.51663977795]
Coordinates of the inscribed circle: I[1.5; 0.64554972244]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 151.0454975628° = 151°2'42″ = 0.50553605103 rad
∠ B' = β' = 133.4332536558° = 133°25'57″ = 0.81327555614 rad
∠ C' = γ' = 75.52224878141° = 75°31'21″ = 1.82334765819 rad

Calculate another triangle




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.

a = 2 ; ; b = 3 ; ; c = 4 ; ;

1. The triangle circumference is the sum of the lengths of its three sides

p = a+b+c = 2+3+4 = 9 ; ;

2. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 9 }{ 2 } = 4.5 ; ;

3. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 4.5 * (4.5-2)(4.5-3)(4.5-4) } ; ; T = sqrt{ 8.44 } = 2.9 ; ;

4. Calculate the heights of the triangle from its area.

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 2.9 }{ 2 } = 2.9 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 2.9 }{ 3 } = 1.94 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 2.9 }{ 4 } = 1.45 ; ;

5. Calculation of the inner angles of the triangle using a Law of Cosines

a**2 = b**2+c**2 - 2bc cos( alpha ) ; ; alpha = arccos( fraction{ a**2-b**2-c**2 }{ 2bc } ) = arccos( fraction{ 2**2-3**2-4**2 }{ 2 * 3 * 4 } ) = 28° 57'18" ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 3**2-2**2-4**2 }{ 2 * 2 * 4 } ) = 46° 34'3" ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 4**2-2**2-3**2 }{ 2 * 3 * 2 } ) = 104° 28'39" ; ;

6. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 2.9 }{ 4.5 } = 0.65 ; ;

7. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 2 }{ 2 * sin 28° 57'18" } = 2.07 ; ;




Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.