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In a triangle with vertices A, B and C and sides a, b and c where a lower case side is opposite the upper case vertex,

a^2 = b^2 + c^2 - 2*b*c*Cos(A).

The second part of the question cannot be answered since "this type of question" is not described!

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Q: What is cosine's law how can solve this type of question?
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Related questions

What are the answers to law of cosines in A plus?

The law of cosines can be written in one form as: c2 = a2 + b2 - 2abCos C. Without 3 of the 4 variables being given, there is no way to answer this question.

Can you use the Law of Cosines to solve a triangle when you are given two side lengths and the included angle measure?

Yes, absolutely

Is this statement true or falseYou can use the Law of Cosines to solve a triangle when you are given the lengths of the three sides and no angle measures?


Who discovered the law of cosines?

A caveman from 10,000 BCal-Kashi was the 1st to provide an explicit statement of the law of cosines in a form suitable for triangulation

What is a form of the law of cosines?

The question asks about the "following". In such circumstances would it be too much to expect that you make sure that there is something that is following?

When would you use the law of sines or law of cosines instead of a trigonometric ratio?

Trigonometric ratios, by themselves, can only be used for right angled triangles. The law of cosines or the sine law can be used for any triangle.

How do you calculate the angles of a triangle knowing the sides?

Law of cosines

Law of cosines with a right angle?

The law of cosines with a right angle is just the pythagorean theorem. The cosine of 90 degrees is 0. That is why the hypotenuse squared is equal to the sum of both of the legs squared

When you have a right angle what does the law of cosines reduce to?

cosine = adjacent/hypotenuse

Can the law of cosines be applied to right and non-right triangles?


How do you find a side of a triangle?

If it's a right triangle, use pythagorean's theorem (a2+b2=c2) to solve it. = If it's an oblique triangle, use the law of sines or cosines (see related link)

Can The law of cosines can only be applied to acute triangles?

No, it applies to all triangles.