Find the Value of h for Sin(x) Approximation

In summary, the conversation discusses finding a value for h that satisfies the equation sin(x)=x - x^3/6 + x^5/120 + R, where |R|<10^(-4) for |x|<h. The participants explore different methods of solving the equation and discuss the use of formulas and principles to evaluate the value of h.
  • #1
mathmathmad
50
0

Homework Statement


find a value of h such that for |x|<h implies sin(x)=x - x^3/6 + x^5/120 + R where |R|<10^(-4)


Homework Equations





The Attempt at a Solution


it's tedious to type out my working but I've got h= (6!/10^4)^1/6 but I'm not sure about this...
 
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  • #2
That certainly works since the difference in sin(x) and your T(x)with your x value is 9.16x10^-6
How did you get this answer?
 
  • #3
blackscorpion said:
That certainly works since the difference in sin(x) and your T(x)with your x value is 9.16x10^-6
How did you get this answer?

I got that (mathmathmad's) as well but I chose x such that I could evaluate without using a calculator. It's not too difficult to be honest. What concerns me is that do we need to prove that sin(x) and its derivatives of all orders are continuous in the given domain or should we take it as given.
 
Last edited:
  • #4
sin(x)=x - x^3/6 + x^5/120 + R

erm, I take |R| = |sin x - x + x^3/6 - x^5/120 |

since R_n = f(x) - T_n (which the value of n I'm not sure of but I take n=5)

and there's a formula which states there exists c in (x,0) such that :
R_n = f^(n+1)(c)*x^(n+1)/(n+1)!

since I take n as 5 then I evaluate |R|<10^(-4) blablabla
get x^6 < 6!/10^4

can we just get the 6th root of 6!/10^4 to evaluate x?

so does h equal to (6!/10^4)^1/6 which is approximately 0.64499...?

please correct me!
 
  • #5
I agree, I've done it with n = 6 but the principles the same.
You guys done the 3rd question?
And if so, how?
 

FAQ: Find the Value of h for Sin(x) Approximation

1. What is the purpose of finding the value of h for Sin(x) approximation?

The purpose of finding the value of h for Sin(x) approximation is to calculate an approximate value for the sine function at a specific angle x. This is useful in various mathematical and scientific applications, such as graphing and solving equations involving trigonometric functions.

2. How is the value of h determined for Sin(x) approximation?

The value of h for Sin(x) approximation is determined using the Taylor series expansion of the sine function. This series involves an infinite sum of terms, but by choosing an appropriate value for h, we can approximate the function with a finite number of terms, providing a close approximation to the actual value.

3. What is the role of h in the Taylor series expansion of the sine function?

The value of h in the Taylor series expansion is known as the step size or interval. It determines the distance between each term in the series and ultimately affects the accuracy of the approximation. A smaller h value will result in a more accurate approximation, but it also requires more computations.

4. Can the value of h be negative in Sin(x) approximation?

No, the value of h cannot be negative in Sin(x) approximation. The Taylor series expansion is based on positive powers of h, and a negative value would result in negative powers, which would not accurately approximate the sine function.

5. Is there a specific formula for finding the value of h for Sin(x) approximation?

Yes, there is a formula for finding the value of h for Sin(x) approximation, known as the "h-formula." It is h = (2n + 1)π /2, where n is the number of terms used in the approximation. This formula provides a good starting point for finding the optimal value of h, but it may need to be adjusted for different values of x or for increased accuracy.

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