... the Law of Cosines (also called the Cosine Rule) says: c 2 = a 2 + b 2 − 2ab cos (C) It helps us solve some triangles. Let's see how to use it.

余弦定理，一般是指在欧氏平面的 三角形 中关于三边长度和一个角度 余弦 值的恒等式。 借助余弦定理，可以在已知三角形两边及其 夹角 的情况下，算出第三边的长度；也可以在已知三边长 …

In trigonometry, the Cosine Rule says that the square of the length of any side of a given triangle is equal to the sum of the squares of the length of the other sides minus twice the product of …

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.

The law of cosines relates the lengths of the sides of a triangle to the cosine of one of its angles. Cosine law in trigonometry generalizes the Pythagoras theorem. Understand the cosine rule …

余弦定理是 三角形 中三边长度与一个角的余弦值 \cos 的数学式，结合下图： 余弦定理是指： c^2=a^2+b^2-2ab\cos\gamma. 同样，也可以将其改为： a^2=b^2+c^2-2bc\cos\alpha. …

餘弦定理是解三角形中的一個重要定理。 餘弦定理可以簡單地變形成： 因此，如果知道了三角形的兩邊及其夾角，可由餘弦定理得出已知角的對邊。 余弦定理可以简单地变形成： …

我们用了几步来做，但其实用 "直接" 公式会比较简单（公式只不过是重排这公式： c2 = a2 + b2 − 2ab cos (C) ）。 公式可以有三个形式： cos (C) = a2 + b2 − c2 2ab. cos (A) = b2 + c2 − a2 …

Decide which formula (Law of Sines/Cosines) you would use to calculate the value of x x below? After you decide that, try to set up the equation (Do not solve -- just substitute into the proper …

The law of cosines (also known as the cosine rule) gives the relationship between the side lengths of a triangle and the cosine of any of its angles. It says —