A tool to demonstrate that parts of the trig function curves are essentially the same.
This tns file, produced by Nevil Hopley, is primarily designed for use by the teacher in demonstration mode but it can be used equally well on the TI-Nspire handheld.
Although calculators and computers allow users to find the value of, for example, sin 248.3° students still need to appreciate the symmetrical nature of the trigonometrical function curves. Indeed they may still face questions in non-calculator examinations that test their understanding of this feature. For example, there is more than one angle whose sine is 0.5 ? why is this and how are they related?
For each of the three basic functions sine, cosine and tangent it is possible to drag a movable point through the first quadrant and see the three related points. The slider in the top left corner of the screen allows you to toggle between degree and radian measurements.
There is a video showing the TI-Nspire document in use at: http://www.handheldgeometry.co.uk/hg/hg114.htm