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# Trigonometry watch

1. (Original post by daviem)
I did that, but I wasn't getting the right answers, I got my primary value as 0.886
Did you work out the angles for -root(3/2)?
2. (Original post by lizard54142)
Oh, well you don't need to find tan(x) as you originally thought in your original post! You just have to square root, and then use inverse tan. Notice though in part b) it is in terms of , but part 1 was just in terms of
but the inverse tan of 2 theta is 0.886 isn't it? That's what I got, but then I don't now how to get the correct values from that
3. (Original post by Bobjim12)
Did you work out the angles for -root(3/2)?
I got that tan2theta is root 1.5, so I did the inverse of that which is where I got 0.886 from
4. I'm confused which bit your stuck on, is it the whole of q 7 or have you shown part a to be true and now your trying to do part b?
5. (Original post by daviem)
I got that tan2theta is root 1.5, so I did the inverse of that which is where I got 0.886 from
Incorrect. Tan2theta is +root 1.5 AND -root 1.5. Square roots can be + and -

ALSO: is your calculator in degrees?
6. (Original post by Nels98)
I'm confused which bit your stuck on, is it the whole of q 7 or have you shown part a to be true and now your trying to do part b?
Yeah, I've done part a and I'm fine on part b up until after tan2theta = = or - root 1.5.
I'm fine up till then, after that I don't have a clue
7. (Original post by Nels98)
I'm confused which bit your stuck on, is it the whole of q 7 or have you shown part a to be true and now your trying to do part b?
(Original post by Bobjim12)
Incorrect. Tan2theta is +root 1.5 AND -root 1.5. Square roots can be + and -

ALSO: is your calculator in degrees?
(Original post by daviem)
Yeah, I've done part a and I'm fine on part b up until after tan2theta = = or - root 1.5.
I'm fine up till then, after that I don't have a clue
There's too many people all trying to help at once. I'll leave you guys to it.
8. (Original post by Bobjim12)
Incorrect. Tan2theta is +root 1.5 AND -root 1.5. Square roots can be + and -

ALSO: is your calculator in degrees?
crap no its in radians, sorry so the primary values are = and - 50.768 then?
9. (Original post by lizard54142)
There's too many people all trying to help at once. I'll leave you guys to it.
I'd more than appreciate your help
10. (Original post by daviem)
crap no its in radians, sorry so the primary values are = and - 50.768 then?
yes, for 2theta
11. but, as I'm sure your aware, there is more to be found. do you know how to do that?
12. (Original post by Nels98)
but, as I'm sure your aware, there is more to be found. do you know how to do that?
No not really, and also this isn't one of the values given in the answer, so do I have to half it?

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14. yeh so for your first value of theta you would just half 50. whatever it was. but to find more values of 2theta within 0-360 you need to use whatever method you were taught such as looking at a tan graph or a quadrant method maybe? then half all those and ensure they are within 0 and 180
15. (Original post by Nels98)
yeh so for your first value of theta you would just half 50. whatever it was. but to find more values of 2theta within 0-360 you need to use whatever method you were taught such as looking at a tan graph or a quadrant method maybe? then half all those and ensure they are within 0 and 180
Sorry if you don't mind explaining how would I find out the values using a tan graph (I know how to draw one), my teacher has been ill for the last few months so we didn't properly go over it.
16. (Original post by Guls)

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To what?
17. essentially for tan you can just ±180 for the rest of the answers. so 50+180=230, 50-180=-130 and 130-180=-310. these are the only values of 2theta in the range of 0-360. half all these to get values of theta. so they are 25, 115, 65 and 155 i think. the reason the negative ones are allowed is as the square root makes it +or -. sorry i couldn't really explain as i am doing the same stuff as you this year so probably no better than you. have to go now but hope this vaguely helped
18. [QUOTE=Nels98;55885933]essentially for tan you can just ±180 for the rest of the answers. so 50+180=230, 50-180=-130 and 130-180=-310. these are the only values of 2theta in the range of 0-360. half all these to get values of theta. so they are 25, 115, 65 and 155 i think. the reason the negative ones are allowed is as the square root makes it +or -. sorry i couldn't really explain as i am doing the same stuff as you this year so probably no better than you. have to go now but hope this vaguely helped[/QUOTE
no thank you that really helped I think I understand it now, thanks very much
19. (Original post by daviem)
Sorry if you don't mind explaining how would I find out the values using a tan graph (I know how to draw one), my teacher has been ill for the last few months so we didn't properly go over it.
Nels explanation on a graph:

After you find these values you must divide by 2 as you have 2x and you want just x
20. Sec^2 it ennit

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