Can you help me solve for arcsin(2) with complex numbers?

  • Thread starter Craptola
  • Start date
In summary, The student is preparing for a math exam and is struggling with complex numbers and algebra. They are trying to solve the problem of finding the value of \arcsin(2) and have attempted to use the equation \sin(z)=\frac{1}{2i}(e^{iz}- e^{-iz}). They are unsure how to rearrange the equation to solve for z and are seeking guidance. Another student suggests making the substitution v=e^{iz} and working backwards from the given equation.
  • #1
Craptola
14
0
Got a maths exam tomorrow been looking through some past papers. Have hit a stumbling block with regard to complex numbers, the problem lies with my algebra.

Homework Statement


Show that [itex]\arcsin(2) = \frac{\pi}{2}-i\ln (2\pm \sqrt3)[/itex]


Homework Equations


I'm fairly certain the way to solve this is to use
[tex]\sin(z)=\frac{1}{2i}(e^{iz}- e^{-iz})[/tex]


The Attempt at a Solution


Equating sin(z) to 2 I could only rearrange it to

[tex]4i=e^{iz}-e^{-iz}[/tex]
I was always pretty awful at algebra and can't see a way to rearrange for z. If anyone could nudge me in the right direction it would be greatly appreciated.
 
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  • #2
The problem becomes simpler if you make the substitution [itex]v=e^{iz}[/itex].
 
  • #3
When the question says "show that a=b", it gives you the option of working from the other end.
 

1. How do you show that arcsin(2) is not a real number?

In order for a number to be a valid input for the arcsine function, it must fall within the range of -1 to 1. Since 2 is greater than 1, it is not a valid input for the arcsine function and therefore, arcsin(2) is not a real number.

2. Can you use a calculator to find the value of arcsin(2)?

No, most calculators are not able to compute the arcsine of a number greater than 1. You would need to use a more advanced calculator or a computer program to find the value of arcsin(2).

3. Why is it important to show that arcsin(2) is not a real number?

It is important because it helps us understand the limitations of the arcsine function. Knowing that certain numbers are not valid inputs for the function allows us to avoid errors and accurately interpret the results of our calculations.

4. Is it possible to approximate the value of arcsin(2)?

Yes, it is possible to use numerical methods to approximate the value of arcsin(2). However, the result will still not be a real number, but rather an approximation of the value.

5. How does the value of arcsin(2) relate to the unit circle?

The value of arcsin(2) represents the angle in radians whose sine is equal to 2. This angle would fall outside of the unit circle, which has a maximum value of 1 for sine and cosine. Therefore, arcsin(2) does not have a direct relation to the unit circle.

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