On-line Math 21

On-line Math 21

3.1  Trigonometric functions

3.1.1  Limits of trig functions

In order to understand the calculus of sin(x) , or any trigonometric function, we first need to find some limits involving trigonometric functions. First, we deal with the limit

lim
x® 0 
 sin(x)
x
 .

To apply the squeeze principle to this situation, we need to look for functions on either side, to compare it to. The picture below shows what we need.

The area of the sector OAB of the unit circle is q/2 (the area of a circular sector with included angle q is qr2/2 , where r is the radius, so if the circle is a unit circle ( r = 1 ), we have what I claimed).

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Copyright (c) 2000 by David L. Johnson.

File translated from TEX by TTH, version 2.61.
On 28 Nov 2000, 16:49.