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# For triangle ABC with sides a, b, and c the law of cosines states the following.

The law of cosine helps in finding the unknown measures of a triangle.

## Answer: The law of cosine states that when all three sides of a triangle are given, we can easily find all the possible angles of the triangle.

Let's understand the concept.

**Explanation:**

Let's observe the triangle ABC with angles A, B and C and sides a, b and c as shown below.

The Law of Cosines (also called the Cosine Rule) states that:

c^{2} = a^{2} + b^{2} − 2ab cos(C)

**Different cosine formulas**

As per the law of cosines formula, to find the length of sides of say △ABC, we can use the following:

- a
^{2}= b^{2}+ c^{2}– 2bc cos A - b
^{2}= a^{2}+ c^{2}– 2ac cos B - c
^{2}= b^{2}+ a^{2}– 2ba cos C

### Hence, the law of cosine states that when all three sides of a triangle are given, we can easily find all the possible angles of the triangle.

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