Triangle calculator SAS

Please enter two sides of the triangle and the included angle
°


Right scalene triangle.

Sides: a = 100   b = 150   c = 180.2787563773

Area: T = 7500
Perimeter: p = 430.2787563773
Semiperimeter: s = 215.1398781887

Angle ∠ A = α = 33.6990067526° = 33°41'24″ = 0.58880026035 rad
Angle ∠ B = β = 56.3109932474° = 56°18'36″ = 0.98327937232 rad
Angle ∠ C = γ = 90° = 1.57107963268 rad

Height: ha = 150
Height: hb = 100
Height: hc = 83.20550294338

Median: ma = 158.1143883008
Median: mb = 125
Median: mc = 90.13987818866

Inradius: r = 34.86112181134
Circumradius: R = 90.13987818866

Vertex coordinates: A[180.2787563773; 0] B[0; 0] C[55.47700196225; 83.20550294338]
Centroid: CG[78.58325277986; 27.73550098113]
Coordinates of the circumscribed circle: U[90.13987818866; -0]
Coordinates of the inscribed circle: I[65.13987818866; 34.86112181134]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 146.3109932474° = 146°18'36″ = 0.58880026035 rad
∠ B' = β' = 123.6990067526° = 123°41'24″ = 0.98327937232 rad
∠ C' = γ' = 90° = 1.57107963268 rad

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How did we calculate this triangle?

1. Calculation of the third side c of the triangle using a Law of Cosines

a = 100 ; ; b = 150 ; ; gamma = 90° ; ; ; ; c**2 = a**2+b**2 - 2ab cos( gamma ) ; ; c = sqrt{ a**2+b**2 - 2ab cos( gamma ) } ; ; c = sqrt{ 100**2+150**2 - 2 * 100 * 150 * cos(90° ) } ; ; c = 180.28 ; ;


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 = 100 ; ; b = 150 ; ; c = 180.28 ; ;

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

p = a+b+c = 100+150+180.28 = 430.28 ; ;

3. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 430.28 }{ 2 } = 215.14 ; ;

4. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 215.14 * (215.14-100)(215.14-150)(215.14-180.28) } ; ; T = sqrt{ 56250000 } = 7500 ; ;

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

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 7500 }{ 100 } = 150 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 7500 }{ 150 } = 100 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 7500 }{ 180.28 } = 83.21 ; ;

6. 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{ 100**2-150**2-180.28**2 }{ 2 * 150 * 180.28 } ) = 33° 41'24" ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 150**2-100**2-180.28**2 }{ 2 * 100 * 180.28 } ) = 56° 18'36" ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 180.28**2-100**2-150**2 }{ 2 * 150 * 100 } ) = 90° ; ;

7. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 7500 }{ 215.14 } = 34.86 ; ;

8. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 100 }{ 2 * sin 33° 41'24" } = 90.14 ; ;




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