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Help your students prepare for their Maths GCSE with this free cosine rule worksheet of 39 questions and answers
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The cosine rule is the relationship between one angle within a triangle and its three sides. The cosine rule states that aΒ²=bΒ²+cΒ²-2bc cos(A) where a, b and c are the lengths of the sides of the triangle and A is the angle opposite side a.Β
The cosine rule can be used to work out missing side lengths and missing angles in non right-angled triangles.Β
To find the missing information, we put the values we know into the cosine rule and then solve the equation to find the missing length. When working out a missing angle we will need to use the inverse trigonometric function cos-1.
Be sure not to round your answers too early in your calculation when using the cosine rule. Also pay close attention to the specified number of decimal places or significant figures in your answer.Β
Β Looking forward, students can then progress to additional geometry worksheets, for example a 3D shapes worksheet or an area of a triangle worksheet.
For more teaching and learning support on Geometry our GCSE maths lessons provide step by step support for all GCSE maths concepts.
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