Triangle calculator

Please enter what you know about the triangle:
Symbols definition of ABC triangle

You have entered side a, b and c.

Right scalene triangle.

Sides: a = 109   b = 60   c = 91

Area: T = 2730
Perimeter: p = 260
Semiperimeter: s = 130

Angle ∠ A = α = 90° = 1.57107963268 rad
Angle ∠ B = β = 33.3988488468° = 33°23'55″ = 0.5832913589 rad
Angle ∠ C = γ = 56.6021511532° = 56°36'5″ = 0.98878827378 rad

Height: ha = 50.09217431193
Height: hb = 91
Height: hc = 60

Median: ma = 54.5
Median: mb = 95.81875349297
Median: mc = 75.30110624095

Inradius: r = 21
Circumradius: R = 54.5

Vertex coordinates: A[91; 0] B[0; 0] C[91; 60]
Centroid: CG[60.66766666667; 20]
Coordinates of the circumscribed circle: U[45.5; 30]
Coordinates of the inscribed circle: I[70; 21]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 90° = 1.57107963268 rad
∠ B' = β' = 146.6021511532° = 146°36'5″ = 0.5832913589 rad
∠ C' = γ' = 123.3988488468° = 123°23'55″ = 0.98878827378 rad

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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 = 109 ; ; b = 60 ; ; c = 91 ; ;

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

p = a+b+c = 109+60+91 = 260 ; ;

2. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 260 }{ 2 } = 130 ; ;

3. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 130 * (130-109)(130-60)(130-91) } ; ; T = sqrt{ 7452900 } = 2730 ; ;

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

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 2730 }{ 109 } = 50.09 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 2730 }{ 60 } = 91 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 2730 }{ 91 } = 60 ; ;

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{ 109**2-60**2-91**2 }{ 2 * 60 * 91 } ) = 90° ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 60**2-109**2-91**2 }{ 2 * 109 * 91 } ) = 33° 23'55" ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 91**2-109**2-60**2 }{ 2 * 60 * 109 } ) = 56° 36'5" ; ;

6. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 2730 }{ 130 } = 21 ; ;

7. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 109 }{ 2 * sin 90° } = 54.5 ; ;




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