Cosine Rule

Below shows △ABC.

You can shift the points B and C to change the size of △ABC.


Instructions:

1. Adjust the size of △ABC.
2. Check the boxes.
3. Observe the values of ${a^2}$ and ${b^2} + {c^2} - 2bc\cos A$.
4. Observe the values of $\cos A$ and $\frac{{{b^2} + {c^2} - {a^2}}}{{2bc}}$.
5. Repeat steps 1 ~ 4 for other sizes of △ABC.

Download the GeoGebra file: http://www.geogebratube.org/material/download/format/file/id/45001

Download the Worksheet: http://db.tt/EgNEyXaF