Solving limits with trig. functions

In summary, the conversation discussed two limit problems and how to solve them. The first problem was split into three separate limits and the second problem was split into the product of three separate limits. The individual limits were then evaluated using algebra and the known limit of sinx/x=1. The expert suggested continuing to work through the problems to find any errors and complete the solutions.
  • #1
mybrainhurts1
4
0
Can anyone help me with these two limit problems...
solve:

lim h->o (h^2-h+sinh)/2h

and

lim y->0 (sin3cot5y)/ycot4y

I know lim x->0 sinx/x=1, but I can't figure out how to get these two into that format.
 
Last edited:
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  • #2
mybrainhurts1 said:
Can anyone help me with these two limit problems...
solve:

lim h->o (h^2-h+sinh)/2h
Split it up into the sum of three separate limits.
mybrainhurts1 said:
and

lim y->0 (sin3cot5y)/ycot4y
Typo here? Should this be lim y->0 (sin3ycot5y)/ycot4y?
If so, split it up into the product of three separate limits, after working with cot5y and cot4y.
mybrainhurts1 said:
I know lim x->0 sinx/x=1, but I can't figure out how to get these two into that format.
 
  • #3
Yes, should be lim y->0 (sin3ycot5y)/ycot4y

So for the first problem--
(h^2/1)-(h/2)+sinh/h= (0^2/1)-(0/2)+1=1...?
 
  • #4
No.
First, you omitted the fact that a limit is involved.
Second, you have multiple algebra errors.
 
  • #5
You're very helpful.
 
  • #6
Are you able to find the errors in the first problem?
 
  • #7
limx->o h^2/2h - limx->0 h/2h + limx->0 sinh/2h, but where do I go from here.
 
  • #8
[tex]\lim_{h \to 0} \frac{h^2}{2h} = (1/2) \lim_{h \to 0} h * \frac{h}{h}=(1/2) \lim_{h \to 0} h * \lim_{h \to 0}\frac{h}{h}[/tex]

It's valid to move constants in or out of the limit, and it's valid to split up limits into sums or products of limits, as long as the individual limits exist.

Can you continue from here for this limit and the other two?
 

What are limits?

Limits are the values that a function approaches as its input values get closer and closer to a specific point.

How do trigonometric functions relate to limits?

Trigonometric functions, such as sine, cosine, and tangent, can be used to model various real-world phenomena. When dealing with limits, these functions can help us understand how a function behaves as the input values approach a certain point.

What are the basic steps for solving limits with trigonometric functions?

The basic steps for solving limits with trig functions include: 1) Simplifying the expression, 2) Evaluating the limit at the specific point, 3) Using trigonometric identities or theorems to rewrite the expression, if necessary, 4) Applying any known limit values, and 5) Simplifying the expression again to find the final limit value.

What are some common techniques for solving limits with trigonometric functions?

Some common techniques for solving limits with trig functions include using the squeeze theorem, converting trigonometric functions to their equivalent algebraic expressions, and using L'Hospital's rule.

What are some common mistakes to avoid when solving limits with trigonometric functions?

Some common mistakes to avoid when solving limits with trig functions include incorrectly applying trigonometric identities or theorems, forgetting to simplify the expression after applying these identities, and assuming that the limit does not exist without fully evaluating it.

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