Help with entering an equation into a calculator

  • Thread starter Etherian
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In summary, the conversation is about trying to enter an equation into a calculator with \theta isolated. The equation relates to the degrees off a liquid crystal will be from the local director depending on the molecule's order parameter. The conversation also mentions using a graphing calculator and the attempt at solving the equation. Finally, the conversation ends with a response providing the correct equation.
  • #1
Etherian
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First I should mention I'm actually going to use this in actionscript (a programming language), but as most people here probably don't know actionscript, I thought a graphing calculator would be a good analogue. I am also using an actual calculator, though, and will from here on regard the question as if it was for the calculator.

Homework Statement


I need to enter this equation into a calculator with [tex]\theta[/tex] isolated:
[tex]S=\frac{3cos^{2}\theta-1}{2}[/tex]
The equation gives how many degrees off a liquid crystal will be from the local director ([tex]\theta[/tex]) depending on on the molecule's order parameter (S). The lower the order parameter the farther off the director the molecule can be. 0 is no order, 1 is perfect order.

Homework Equations


I need to type this into a calculator where S is the input and [tex]\theta[/tex] is the output. I'm only in 8th grade and we haven't worked with these kind of equations yet, as simple as it is, so I'm not sure how to type it, let alone isolate [tex]\theta[/tex].

The Attempt at a Solution


I haven't tried isolating [tex]\theta[/tex] yet as can't even type the original it in correctly.
What I have so far is S=(3[cos([tex]\theta[/tex])^2]-1)/2.
This looks correct to me, but when I enter a number for S it gives a result I don't believe could be correct. I have entered it two or three times and, unfortunately, I seemed to have entered it differently both times, giving me an even less realistic output.

I need a response fairly quickly, since the project is due tomorrow. Thanks in advance to anyone that helps.
 
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  • #2
Etherian said:
First I should mention I'm actually going to use this in actionscript (a programming language), but as most people here probably don't know actionscript, I thought a graphing calculator would be a good analogue. I am also using an actual calculator, though, and will from here on regard the question as if it was for the calculator.

Homework Statement


I need to enter this equation into a calculator with [tex]\theta[/tex] isolated:
[tex]\frac{3cos^{2}\theta-1}{2}[/tex]
The equation gives how many degrees off a liquid crystal will be from the local director ([tex]\theta[/tex]) depending on on the molecule's order parameter (S). The lower the order parameter the farther off the director the molecule can be. 0 is no order, 1 is perfect order.

Homework Equations


I need to type this into a calculator where S is the input and [tex]\theta[/tex] is the output. I'm only in 8th grade and we haven't worked with these kind of equations yet, as simple as it is, so I'm not sure how to type it, let alone isolate [tex]\theta[/tex].

The Attempt at a Solution


I haven't tried isolating [tex]\theta[/tex] yet as can't even type the original it in correctly.
What I have so far is S=(3[cos([tex]\theta[/tex])^2]-1)/2.
This looks correct to me, but when I enter a number for S it gives a result I don't believe could be correct. I have entered it two or three times and, unfortunately, I seemed to have entered it differently both times, giving me an even less realistic output.

I need a response fairly quickly, since the project is due tomorrow. Thanks in advance to anyone that helps.
If [itex]S=(3[cos^2(\theta)]-1)/2[/tex]. then [itex]2S= 3 cos^2(\theta)- 1[/itex], [itex]2S+ 1= 3 cos^2(\theta)[/itex], [itex](2S+1)/3= cos^2(\theta)[/itex], [itex]\sqrt{(2S+1)/3}= cos(\theta)[/itex] and, finally, [itex]\theta= cos^{-1}(\sqrt{(2S+1)/3})[/itex].

That "cos-1" is, of course, the inverse- or arc-cosine, not the reciprocal.
 
  • #3
Thanks for responding so quickly (in fact faster than I was able to edit my own post). The equation still won't work, but I believe it is that I misunderstood the equation, than it was incorrect or someone did something wrong. Thanks again for the help.
 

1. How do I enter an equation into a calculator?

To enter an equation into a calculator, you will need to use the appropriate mathematical symbols and follow the correct order of operations. Start by typing in the numbers and then use the appropriate buttons for addition, subtraction, multiplication, and division. Use parentheses to group parts of the equation together and indicate which operations should be performed first.

2. Can I enter multiple equations into a calculator at once?

Some calculators have the ability to store and recall multiple equations, but most can only handle one equation at a time. If you need to solve multiple equations, you will have to enter them one by one.

3. What if I make a mistake while entering an equation?

If you make a mistake while entering an equation, most calculators have a delete or backspace button that will allow you to correct the error. Some calculators also have a clear or reset button that will erase the entire equation and let you start over.

4. Can I use letters or variables in my equation?

Most calculators do not have the ability to solve equations with variables. However, some scientific or graphing calculators do have this capability. If you need to solve an equation with variables, make sure to check your calculator's manual to see if it is possible.

5. How do I enter exponents or roots into a calculator?

To enter an exponent, use the "^" symbol. For example, to calculate 2 to the power of 3, you would enter "2^3" into the calculator. To enter a square root, use the "√" symbol. For example, to calculate the square root of 25, you would enter "√25" into the calculator. Some calculators also have specific buttons for exponents and roots.

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