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Calculating with Cosines

Age 14 to 18
Challenge Level Yellow starYellow star
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Try to make sense of each method shown one line at a time. The following mathematical topics may be useful:

 

Pythagoras' theorem

Trigonometry in right-angled triangles

Cosines of angles greater than $90^{\circ}$

Distance between two points on a coordinate grid

 

 

 

 

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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