Triangle calculator SSS - result

Please enter the triangle sides:


Acute isosceles triangle.

Sides: a = 4   b = 10   c = 10

Area: T = 19.59659179423
Perimeter: p = 24
Semiperimeter: s = 12

Angle ∠ A = α = 23.07439180656° = 23°4'26″ = 0.40327158416 rad
Angle ∠ B = β = 78.46330409672° = 78°27'47″ = 1.3699438406 rad
Angle ∠ C = γ = 78.46330409672° = 78°27'47″ = 1.3699438406 rad

Height: ha = 9.79879589711
Height: hb = 3.91991835885
Height: hc = 3.91991835885

Median: ma = 9.79879589711
Median: mb = 5.74545626465
Median: mc = 5.74545626465

Inradius: r = 1.63329931619
Circumradius: R = 5.10331036308

Vertex coordinates: A[10; 0] B[0; 0] C[0.8; 3.91991835885]
Centroid: CG[3.6; 1.30663945295]
Coordinates of the circumscribed circle: U[5; 1.02106207262]
Coordinates of the inscribed circle: I[2; 1.63329931619]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 156.9266081934° = 156°55'34″ = 0.40327158416 rad
∠ B' = β' = 101.5376959033° = 101°32'13″ = 1.3699438406 rad
∠ C' = γ' = 101.5376959033° = 101°32'13″ = 1.3699438406 rad

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How did we calculate this triangle?

a = 4 ; ; b = 10 ; ; c = 10 ; ;

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

p = a+b+c = 4+10+10 = 24 ; ;

2. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 24 }{ 2 } = 12 ; ;

3. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 12 * (12-4)(12-10)(12-10) } ; ; T = sqrt{ 384 } = 19.6 ; ;

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

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 19.6 }{ 4 } = 9.8 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 19.6 }{ 10 } = 3.92 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 19.6 }{ 10 } = 3.92 ; ;

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{ 4**2-10**2-10**2 }{ 2 * 10 * 10 } ) = 23° 4'26" ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 10**2-4**2-10**2 }{ 2 * 4 * 10 } ) = 78° 27'47" ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 10**2-4**2-10**2 }{ 2 * 10 * 4 } ) = 78° 27'47" ; ;

6. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 19.6 }{ 12 } = 1.63 ; ;

7. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 4 }{ 2 * sin 23° 4'26" } = 5.1 ; ;

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