Triangle calculator ASA

Please enter the side of the triangle and two adjacent angles
°
°


Equilateral triangle.

Sides: a = 200   b = 200   c = 200

Area: T = 17320.50880757
Perimeter: p = 600
Semiperimeter: s = 300

Angle ∠ A = α = 60° = 1.04771975512 rad
Angle ∠ B = β = 60° = 1.04771975512 rad
Angle ∠ C = γ = 60° = 1.04771975512 rad

Height: ha = 173.2055080757
Height: hb = 173.2055080757
Height: hc = 173.2055080757

Median: ma = 173.2055080757
Median: mb = 173.2055080757
Median: mc = 173.2055080757

Inradius: r = 57.7355026919
Circumradius: R = 115.4770053838

Vertex coordinates: A[200; 0] B[0; 0] C[100; 173.2055080757]
Centroid: CG[100; 57.7355026919]
Coordinates of the circumscribed circle: U[100; 57.7355026919]
Coordinates of the inscribed circle: I[100; 57.7355026919]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 120° = 1.04771975512 rad
∠ B' = β' = 120° = 1.04771975512 rad
∠ C' = γ' = 120° = 1.04771975512 rad

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How did we calculate this triangle?

1. Calculate the third unknown inner angle

 alpha = 60° ; ; beta = 60° ; ; ; ; alpha + beta + gamma = 180° ; ; ; ; gamma = 180° - alpha - beta = 180° - 60° - 60° = 60° ; ;

2. By using the law of sines, we calculate unknown side a

c = 200 ; ; ; ; fraction{ a }{ c } = fraction{ sin( alpha ) }{ sin ( gamma ) } ; ; ; ; a = c * fraction{ sin( alpha ) }{ sin ( gamma ) } ; ; ; ; a = 200 * fraction{ sin(60° ) }{ sin (60° ) } = 200 ; ;

3. By using the law of sines, we calculate last unknown side b

 fraction{ b }{ c } = fraction{ sin( beta ) }{ sin ( gamma ) } ; ; ; ; b = c * fraction{ sin( beta ) }{ sin ( gamma ) } ; ; ; ; b = 200 * fraction{ sin(60° ) }{ sin (60° ) } = 200 ; ;


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 = 200 ; ; b = 200 ; ; c = 200 ; ;

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

p = a+b+c = 200+200+200 = 600 ; ;

5. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 600 }{ 2 } = 300 ; ;

6. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 300 * (300-200)(300-200)(300-200) } ; ; T = sqrt{ 300000000 } = 17320.51 ; ;

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

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 17320.51 }{ 200 } = 173.21 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 17320.51 }{ 200 } = 173.21 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 17320.51 }{ 200 } = 173.21 ; ;

8. 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{ 200**2-200**2-200**2 }{ 2 * 200 * 200 } ) = 60° ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 200**2-200**2-200**2 }{ 2 * 200 * 200 } ) = 60° ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 200**2-200**2-200**2 }{ 2 * 200 * 200 } ) = 60° ; ;

9. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 17320.51 }{ 300 } = 57.74 ; ;

10. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 200 }{ 2 * sin 60° } = 115.47 ; ;




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