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Tutorial on the law of sines and cosines and on how to decide which formula to use in triangle problems.
To find angles and distances on this imaginary sphere, astronomers invented techniques that are now part of spherical trigonometry. The laws of sines and cosines were first stated in this context, in a slightly different form than the laws for plane trigonometry.
In trigonometry, the law of cosines (also known as the cosine formula or cosine rule) relates the lengths of the sides of a triangle to the cosine of one of its angles.
Law of sines and cosines' illustration. The law of sines is useful for computing the lengths of the unknown sides in a triangle if two angles and one side are known. [5]
The Law of Sines (or Sine Rule) is very useful for solving triangles: a sin A = b sin B = c sin C. It works for any triangle: a, b and c are sides. A, B and C are angles.
Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/trigonometry/less-basic-trigonometry/law-sines-cosines/e/law_of_...
The law of sines is one of two trigonometric equations commonly applied to find lengths and angles in scalene triangles, with the other being the law of cosines. The law of sines can be generalized to higher dimensions on surfaces with constant curvature.
