# The Derivative of the Sine

### Introduction

The applet and the left side figure show
The large circle is the unit circle. The red line segment has the length
sin(x+h)-sin x. Observe the change of the red segment using the
applet and consider what is the relation between the angle x and the
length of the red segment.

If the small circle is the unit circle, what dose the red line segment correspond to?

### Applet