Cosine rule

The cosine rule
You can help to support future videos on Patreon:   / graphicmaths  

This video explains the cosine rule.

The cosine rule can be used to solve any triangle where either two sides and the enclosed angle are known, or where three sides are known. As a result of applying the cosine rule we will know three sides and one angle. The sine rule can then be applied to find the remaining angle.

We also look at the cosine rule can't be applied to two sides and a non-included angle. And we see haw the cosine rule becomes equivalent to Pythagoras' theorem when the angle is 90 degrees.

Suitable for UK GCSE, IB MYP, US grades 9+. Typically taught to students aged 14 and above.

Other videos:
Sine rule:    • GCSE Higher Maths Trigonometry - sine...  

Related articles:
Cosine rule: https://graphicmaths.com/gcse/trigono...
Sine rule: https://graphicmaths.com/gcse/trigono...

Links:
Website: https://graphicmaths.com text versions of these videos.
Twitter:   / graphicmaths  
Reddit:   / graphicmaths  
Patreon:   / graphicmaths   please consider becoming a patron to support this channel.

This video was created using generativepy, a free and open source Python library for creating mathematical art and animations, available from https://github.com/martinmcbride/gene...