Chapter 2: Problem 35
Are the functions continuous at the point being approached? \(\lim _{t \rightarrow 0} \cos \left(\frac{\pi}{\sqrt{19-3 \sec 2 t}}\right)\) 3
Short Answer
Expert verified
Yes, the function is continuous at \( t = 0 \).
Step by step solution
01
Understand the Function
We need to check if the function \( f(t) = \cos\left(\frac{\pi}{\sqrt{19 - 3 \sec 2t}}\right) \) is continuous at \( t = 0 \). For this, we need to evaluate the behavior of \( \sec 2t \) as \( t \to 0 \).
02
Evaluate \( \sec 2t \) as \( t \to 0 \)
The function \( \sec 2t = \frac{1}{\cos 2t} \) will converge to \( \sec 0 = 1 \) since \( \cos 0 = 1 \). Substitute this into the original function.
03
Substitute into the function
Plugging \( \sec 0 = 1 \) into the function, we get \( \frac{\pi}{\sqrt{19 - 3\cdot 1}} \). Simplifying, this becomes \( \frac{\pi}{\sqrt{16}} = \frac{\pi}{4} \).
04
Evaluate the Cosine Function
Now substitute back into \( \cos\left(\frac{\pi}{4}\right) \). From trigonometric identities, \( \cos\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2} \).
05
Check and Conclude Continuity
The limit as \( t \to 0 \) exists and evaluates to a finite value \( \frac{\sqrt{2}}{2} \). Therefore, the function is continuous at \( t = 0 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Limits
In calculus, limits help us describe the behavior of a function as it approaches a certain point. Understanding limits is essential because they form the foundation for defining many other important concepts in calculus, such as derivatives and continuity.
- A limit looks at what happens to function values as inputs get close to a specific point without necessarily touching the point.
- For example, in our exercise, we're interested in what happens to the function \( f(t) = \cos\left(\frac{\pi}{\sqrt{19 - 3 \sec 2t}}\right) \) as \( t \to 0 \).
Trigonometric Functions
Trigonometric functions like cosine, sine, and tangent are critical in calculus because they describe the geometry of waves and other cyclical patterns.
- The cosine function, denoted as \( \cos \), outputs values ranging from -1 to 1 depending on the angle you input.
- In our situation, \( \cos\left(\frac{\pi}{4}\right) \) returns \( \frac{\sqrt{2}}{2} \), which is a well-known trigonometric value often used in unit circle calculations.
Evaluating Limits
To evaluate limits, especially when involving trigonometric or other complex functions, a methodical approach is vital. Here's how we approached evaluating the limit in our example:
- First, understand the function and identify tricky parts, like \( \sec 2t \).
- Simplify by finding the behavior of components as the input approaches the point of interest, here \( t = 0 \).
- Substitute these simplified behaviors back into the main function to resolve any indeterminate forms.