Proving the limit of sinx/x as x approaches 0 equals 1

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In summary, the conversation is about a geometric proof from James Stewart's calculus textbook, specifically on page 192. The person is confused about the sequence of inequalities in the proof, specifically how EB turned into ED. They ask for clarification and the expert responds by explaining that in the first diagram, it is clear that |EB| < |ED|, and this leads to the substitution. The substitution allows for the expression to be reduced to one involving straight segments related to theta by trigonometric functions. The expert also notes that point D was described earlier in the proof and it should be clear that |ED| > |EB|.
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Terrell
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this is a geometric proof from James Stewart's calculus textbook page 192. I'm confused in the sequence of inequalities as part of the proof...
theta = arcAB < AB + EB ==> arcAB < AE + ED. How did EB turned into ED?
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In the first diagram, it' easy to see that ##\left|EB\right| < \left|ED\right|##, so what you ask follows. Then there are just substitutions.
 
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Point D was described in the first half of the proof. It should be clear that |ED| > |EB|.
The benefit of doing the substitution is that you can reduce the expression to one involving straight segments related to theta by trigonometric functions.
##\tan \theta = \frac{|AD|}{|OA|}##
 
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What is the definition of a limit?

A limit is a mathematical concept that describes the behavior of a function as its input approaches a certain value or point. It is used to determine the value that a function approaches as its input gets closer and closer to a specific value.

What is the limit of sinx/x as x approaches 0?

The limit of sinx/x as x approaches 0 is equal to 1.

How do you prove the limit of sinx/x as x approaches 0 equals 1?

The limit can be proven using the definition of a limit, which states that for a function f(x), the limit as x approaches a is equal to L if for every positive number ε, there exists a positive number δ such that whenever 0 < |x - a| < δ, then |f(x) - L| < ε. In the case of sinx/x as x approaches 0, we can use the Squeeze Theorem to show that the limit is equal to 1.

Why is the limit of sinx/x as x approaches 0 important?

The limit of sinx/x as x approaches 0 is important because it is a fundamental concept in calculus and is used in many applications. It also helps to explain the behavior of trigonometric functions and is a crucial step in finding derivatives and integrals of these functions.

Are there any other ways to prove the limit of sinx/x as x approaches 0 equals 1?

Yes, there are other methods such as using trigonometric identities or using the definition of a derivative. However, the Squeeze Theorem is the most commonly used method to prove this limit.

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