**Symmetry in Trigonometry**The green slider determines the angle

The angle is equal to .
Move the green slider to the left and right, and watch how points and are always
symmetrical to one another about the and , are symmetric about the and
Pairs of points that are symmetric about the

*x*-axis. If two points, such as*x*-axis, - How must their*x*-coordinates be related? - How must their*y*-coordinates be related? The graph above illustrates the*x*-axis symmetry displayed by the angles*x*-axis will**always**: - have the same*x*-coordinates - have*y*-coordinates that are the negative of one another If you wish to use other applets similar to this, you may find an index of all my applets here: https://mathmaine.com/2010/04/27/geogebra/