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Is my calculator giving the wrong score or ? (Simple calculation question)

  • #1
Femme_physics
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This is actually just a simple calculator question.

See, according to this paper I attached, (2sin{pi/2})^5 equals 32. When I plug it into the calculator, I get 4.95 x 10^-7

Just wonder what's wrong with this picture..?
 

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  • #2
Doc Al
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When I plug it into the calculator, I get 4.95 x 10^-7
What are you plugging in?
 
  • #3
Femme_physics
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This -> (2sin{pi/2})^5

It's also in the file I attached (they're talking about limits but ignore that, I'm just trying to get the calculator figure correct), and their answer inexplicably turns out 32 while mine is a ridiculous seemingly unrelated number.
 
  • #4
Doc Al
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This -> (2sin{pi/2})^5

It's also in the file I attached, but their answer inexplicably turns out 32 while mine is a ridiculous seemingly unrelated number.
What does your calculator give you for this: sin{pi/2}

(Make sure you're in the correct mode.)
 
  • #5
HallsofIvy
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I rather suspect (as Doc Al does) that you have your calculator in "degree" mode. You want it in "radian" mode.

And frankly, at the level this problem indicates, you should not have to use your calculator to find "[itex]sin(\pi/2)[/itex]".
 
  • #6
eumyang
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And frankly, at the level this problem indicates, you should not have to use your calculator to find "[itex]sin(\pi/2)[/itex]".
If my precalculus students are any indication, you'd be surprised. :cry:
 
  • #7
statdad
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"And frankly, at the level this problem indicates, you should not have to use your calculator to find [itex] \sin({\pi}/2} [/itex]"

I agree with this statement, but it seems to be less and less a reflection of reality. I constantly battle with our head of institutional research on this: Her: "Memorization doesn't take different methods of learning or current brain research into account." Me: ???
 
  • #8
Femme_physics
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What does your calculator give you for this: sin{pi/2}

(Make sure you're in the correct mode.)
It gives me 0.02741....

I suspect you're all right and it's all about the wrong mode. Thanks :)
I rather suspect (as Doc Al does) that you have your calculator in "degree" mode. You want it in "radian" mode.

And frankly, at the level this problem indicates, you should not have to use your calculator to find "".
You mean I ought to solve it manually?
 
  • #9
D H
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It gives me 0.02741....

I suspect you're all right and it's all about the wrong mode. Thanks :)
You are missing the point. You should not be using your calculator to solve this problem. Period. You should be able to solve this problem in your head. Regarding [itex]\sin(\pi/2)[/itex]: No calculation is needed. You should know this. Regarding 25: You should be able to compute this in your head without a calculator.

Over reliance on calculators is a bad habit.
 
  • #10
Femme_physics
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Well, we haven't been dealing with radians, really, so I just thought pi/2 means 3.14 divided by 2....I didn't know it translates to 90 deg.
 
  • #11
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Like all others said before me, do not rely on the calculator to do your work, but rather, use it to check your work. This problem should take a maximum of 5 seconds to solve in your head. By now, you should have seen the Unit Circle. I cannot stress enough how much it is to know the unit circle as it will be your best friend in Trigonometry and Pre-Calculus (Trig section). I keep helping my younger brother in math and constantly tell him to know the unit circle. You don't need to know all of it either. If you can remember just the first quadrant, you should be able to figure out the entire circle. Please print yourself a copy of it and study it.
 
  • #12
HallsofIvy
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Well, we haven't been dealing with radians, really, so I just thought pi/2 means 3.14 divided by 2....I didn't know it translates to 90 deg.
Excellent. And what is the sine of 90 degrees?
 

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