Stuck on Trigonometry equations problem Watch

Sir Phillip Jones
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#21
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#21
(Original post by TenOfThem)
Do they give the correct answer - if so they are correct - you can check that
How do i go about checking it?
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TenOfThem
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#22
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#22
(Original post by Sir Phillip Jones)
How do i go about checking it?
you think that \theta = 45

you need \sin 2\theta = 1

does it
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Sir Phillip Jones
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#23
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#23
(Original post by TenOfThem)
you think that \theta = 45

you need \sin 2\theta = 1

does it
I think it does.

\sin 2\theta is Sin (2 x 45) which is Sin 90

Sin^-1 90 = 1

So 45 is the 5th solution right? To work out the last one, i do 180 + 45. Is that correct?
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TenOfThem
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#24
(Original post by Sir Phillip Jones)
To work out the last one, i do 180 + 45. Is that correct?
again - you can check
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Sir Phillip Jones
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#25
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#25
(Original post by TenOfThem)
again - you can check
Sorry but i don't know how to check? I thought i did? Lost here :confused:
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TenOfThem
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(Original post by Sir Phillip Jones)
Sorry but i don't know how to check? I thought i did? Lost here :confused:
You think that \theta = 45 + 180 = 225

You need \sin 2\theta = 1

I am not sure what you are struggling with but I would suggest that you tell your teacher that you needed A LOT of help on this and ask him/her to go through it again with you
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Sir Phillip Jones
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#27
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#27
(Original post by TenOfThem)
You think that \theta = 45 + 180 = 225

You need \sin 2\theta = 1

I am not sure what you are struggling with but I would suggest that you tell your teacher that you needed A LOT of help on this and ask him/her to go through it again with you
Yes i will do that. And i really appreciate the help you've given me up to this point. Could you be a saint and explain to me how you get the final 2 solutions. I feel like i'm going round in circles, and my head will explode. I will then hopefully be able to work out how you did it, and check each solution individually to see if it's right.


So is 45 correct? And then to work out the other it's actually, 270/2 which is 135? So 45 and 135 is right and NOT 45, 225?
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TenOfThem
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(Original post by Sir Phillip Jones)
Yes i will do that. And i really appreciate the help you've given me up to this point. Could you be a saint and explain to me how you get the final 2 solutions. I feel like i'm going round in circles, and my head will explode. I will then hopefully be able to work out how you did it, and check each solution individually to see if it's right.


So is 45 correct? And then to work out the other it's actually, 270/2 which is 135? So 45 and 135 is right and NOT 45, 225?

You need \sin 2\theta = 1

135 gives \sin 270 = -1
225 gives \sin 450 = 1
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Sir Phillip Jones
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#29
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#29
(Original post by TenOfThem)
You need \sin 2\theta = 1

135 gives \sin 270 = -1
225 gives \sin 450 = 1


Still lost here. What do you mean by i need \sin 2\theta = 1. What am i supposed to do with this? How do i get the remaining 2 solutions from this?
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TenOfThem
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#30
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#30
(Original post by Sir Phillip Jones)
Still lost here. What do you mean by i need \sin 2\theta = 1. What am i supposed to do with this? How do i get the remaining 2 solutions from this?
What were you trying to solve

Look at your own posts 9 and 13
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Sir Phillip Jones
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#31
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#31
(Original post by TenOfThem)
What were you trying to solve

Look at your own posts 9 and 13
Right, i think i've cracked it now. Thanks for the help. I understand now what you mean by being able to check myself Sorry about that

The 6 solutions are: 45, 210, 225, 285, 330 & 345
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TenOfThem
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#32
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#32
(Original post by Sir Phillip Jones)
...
Maths Meetings.pdf

you forgot to halve your 210
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Sir Phillip Jones
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#33
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#33
(Original post by TenOfThem)
Maths Meetings.pdf

you forgot to halve your 210
Ah yes. Silly mistake there. Thanks very much
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