# Homework Help: Why did my teacher give points off for saying the tangent of 180 and 360 degrees = 0?

1. Mar 20, 2012

### e^(i Pi)+1=0

????
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 20, 2012

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Why do you think your teacher gave "points off"?

3. Mar 20, 2012

### Mentallic

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

You need to be more specific. What was the question?

Maybe you were restricted to the values of $-\pi/2$ to $\pi/2$ for example.

4. Mar 20, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I guess I should have given more information. It was a no-calculator test. The part I'm talking about you had to fill in the famous unit circle chart.

5. Mar 20, 2012

### HallsofIvy

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Then perhaps you were expected to say $tan(\pi)= tan(2\pi)= 0$ rather than using degrees.

6. Mar 20, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

7. Mar 20, 2012

### Staff: Mentor

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Your instructor probably dinged you for writing ∅ (empty set) instead of 0. He or she might have been confused because you write ∅ in some places and 0 in others, without consistency.

8. Mar 20, 2012

### HallsofIvy

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

However, he/she did not take points off for that same answer for $\theta= 0$. I'm confused!

9. Mar 20, 2012

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Could be speed marking and the teacher overlooked it.Having had another look it seems as if he/she deducted four marks(-1 and -3)

Last edited: Mar 20, 2012
10. Mar 20, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

No, it was only -1. There was also a -2 higher up on the page.

11. Mar 20, 2012

### Mentallic

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Why don't you ask her why she removed the marks?

12. Mar 20, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Oh I plan to...

13. Mar 20, 2012

### jey1234

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I'm pretty sure it's what Mark44 said and she probably won't change her mind but it's always worth asking

14. Mar 21, 2012

### Mentallic

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I doubt that's the case, because for one, she wasn't consistent in dragging down marks for each time he wrote the empty set, also, it's sometimes common practice to write zero with the slanted line through it to denote that it is in fact zero as opposed to the letter O. And finally, if he's answering simple trig questions, I doubt they've learnt about sets yet.

15. Mar 22, 2012

### Staff: Mentor

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I think I, too, would have deducted marks, as it appears you changed a 1 to a 0, or a 0 to a 1, and it's not clear what your final answer is supposed to be. Or else you are hedging your bets and hoping to be given the benefit of the doubt whatever the correct answer may be. :tongue:

16. Mar 22, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

What are you talking about? Where did I change a one to a zero?

17. Mar 22, 2012

### Staff: Mentor

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

You crossed zero can be interpreted as you changed 1 to 0 (or vice versa). Doesn't mean you did, but it is not necessarily obvious you didn't.

18. Mar 22, 2012

### Ray Vickson

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Nobody said you did; they just said it looked like you might have, and that is probably why marks were taken off. (A 0 with a line through it *might* be interpreted as a zero crossed out, rather than a zero.)

RGV

19. Mar 23, 2012

### micromass

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

Why did you write 0 in some place and $\emptyset$ in other places??

20. Mar 23, 2012

### e^(i Pi)+1=0

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

No reason. I always put a slash through my zeros but just forgot here for some reason.

21. Mar 23, 2012

### scurty

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

That's probably a habit you should try to break. Even as early as Calculus the null set it used, it will just cause confusion.

The earliest time in my math career that I could remember using the letter O to denote something was in Topology to denote open sets. It's a pretty safe bet you won't be confusing Os with 0s. I'd say the only necessary "strike through a symbol" you need to do is for zs to not confuse them with 2s.

22. Mar 23, 2012

### tiny-tim

don't

stop it!

you must use the same notation as the rest of your community

well worth losing 1 point to correct this

23. Mar 23, 2012

### Curious3141

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I think you should argue your case. It is a recognised alternative notation, even though you used it somewhat inconsistently here. You don't deserve to have those marks subtracted away for having a concept that's right, and having represented that concept on paper in a reasonably acceptable fashion. In your place, I'd fight for the marks, especially if they mattered.

The "cancellation" interpretation doesn't hold water, because a cancellation should be accompanied by a correction (replacement text). Obviously, that's not the case here.

To those arguing that he should be adhering to strict popular conventions, well, what about in other cases, for e.g. when a student write a '7' with a line through the middle (as I do)? In some places, that's common; whereas in others, it isn't. Should a student calmly accept it if a teacher marks him wrong for that?

There's no question of confusion with the 'empty set' notation in this instance, either.

24. Mar 23, 2012

### Mentallic

Re: Why did my teacher give points off for saying the tangent of 180 and 360 degrees

I agree with Curious, but I should stress that you'll probably be better off not pushing the subject about those marks if they don't mean anything significant. Just mention it to your teacher so both you and him/her can be aware of what happened and of what could be changed for future reference.

Don't come off as someone that tries to force as many changes after marking out as possible, because I've seen other fellow students do that and it doesn't bode well for them in the end. It'll make your case stronger if you do think you deserve marks later on in tests that matter.

25. Mar 23, 2012

### tiny-tim

but a '7' with a line through the middle is still a number

an 'O' with a line through it (protruding on either side) is something else