Calculatrice de la Loi des Sinus Gratuite

Résolvez des triangles avec la loi des sinus. Trouvez les côtés et angles manquants à partir du rapport a/sin(A).

deg
deg

Side B

17.3205

Angle C90.00 deg
Side C20.0000

Formule

Law of Sines

Formula

a / sin(A) = b / sin(B) = c / sin(C)

This law relates the sides of any triangle to the sines of their opposite angles.

Solving for Side b

b = a × sin(B) / sin(A)

When to Use

Use the Law of Sines when you know:

  • Two angles and one side (AAS or ASA)
  • Two sides and an angle opposite one of them (SSA, but watch for the ambiguous case)
  • Exemple Résolu

    Find side b: a = 10, angle A = 30°, angle B = 60°.

    1. 01b = 10 × sin(60°) / sin(30°)
    2. 02= 10 × 0.8660 / 0.5
    3. 03= 17.3205
    4. 04Angle C = 180 - 30 - 60 = 90°

    Questions Fréquentes

    What is the law of sines?

    The law of sines states that in any triangle, the ratio of a side length to the sine of its opposite angle is constant: a/sin(A) = b/sin(B) = c/sin(C).

    What is the ambiguous case?

    When given two sides and a non-included angle (SSA), there may be zero, one, or two possible triangles. This is the ambiguous case of the law of sines.

    When should I use law of sines vs law of cosines?

    Use law of sines for AAS, ASA, or SSA problems. Use law of cosines for SAS or SSS problems.

    Apprendre

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