In the app we investigate two very important trigonometric limits. These two limits are critical to finding derivative formulas for the sine and cosine functions. [br][br]Both limits are taken as x approaches 0. For the function sin(x)/x we can display the limit process to see that we can sandwich theta between sin([math]\theta[/math]) and tan([math]\theta[/math]). With some manipulation, we find that this gives us [br]cos([math]\theta[/math])<sin([math]\theta[/math])/[math]\theta[/math] < 1. Move the point B in the right window to manipulate the value of the red arclength, [math]\theta[/math] , which equals the x-value in the left window. As x = [math]\theta[/math] approaches 0, we see that the function values approach 1, by the Squeeze Theorem.[br][br]We use this limit to obtain the other limit.