I’ve spent several hours on this problem trying to attack it different ways and I finally got to a conclusion (or 2). I got 2 answers for the problem so was hoping if anyone could check my work (and tell me if I’ve gone wrong or if it’s correct) or perhaps work it out themselves and then compare answers?
This problems really bugged me and I just feel like I’ve gone wrong. I’ve labelled my working out in stages so hopefully you can follow it.
Thanks
This is the question
Here is my workings:
https://imgur.com/a/rF82L
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Y11_Maths
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- 14-03-2018 22:47
Posted on the TSR App. Download from Apple or Google PlayLast edited by Y11_Maths; 14-03-2018 at 22:54. -
Notnek
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- 14-03-2018 23:07
(Original post by Y11_Maths)
I’ve spent several hours on this problem trying to attack it different ways and I finally got to a conclusion (or 2). I got 2 answers for the problem so was hoping if anyone could check my work (and tell me if I’ve gone wrong or if it’s correct) or perhaps work it out themselves and then compare answers?
This problems really bugged me and I just feel like I’ve gone wrong. I’ve labelled my working out in stages so hopefully you can follow it.
Thanks
This is the question
Here is my workings:
https://imgur.com/a/rF82L -
RogerOxon
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- 14-03-2018 23:07
(Original post by Y11_Maths)
I’ve spent several hours on this problem trying to attack it different ways and I finally got to a conclusion (or 2). I got 2 answers for the problem so was hoping if anyone could check my work (and tell me if I’ve gone wrong or if it’s correct) or perhaps work it out themselves and then compare answers?
This problems really bugged me and I just feel like I’ve gone wrong. I’ve labelled my working out in stages so hopefully you can follow it.
Thanks
This is the question
Here is my workings:
https://imgur.com/a/rF82L
From the diagram, we need to take.
Posted on the TSR App. Download from Apple or Google PlayLast edited by RogerOxon; 14-03-2018 at 23:14. -
Y11_Maths
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- 14-03-2018 23:16
(Original post by RogerOxon)
The point (r-9, r-8) lies on the circle.
From the diagram, we need to take.
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Y11_Maths
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- 14-03-2018 23:19
(Original post by RogerOxon)
The point (r-9, r-8) lies on the circle.
From the diagram, we need to take.
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ghostwalker
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- 14-03-2018 23:25
(Original post by Y11_Maths)
Yep I just spotted that. Going to absolutely cry myself to sleep tonight! What an absolute mug I feel, thanks.
From what I can tell of your image in imgur, you've assumed that a line from the centre to the corner passes through the corner of the small oblong, which is not the case.
Here's an exagerated blow-up. -
Notnek
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- 14-03-2018 23:27
(Original post by Y11_Maths)
So where actually did I go wrong in my workings(assuming there is more than 1 way to work it out)? Since I was only 1 away from the answer...?
ghostwalker beat me and his post is inifinitely better since it contains a diagram -
Y11_Maths
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- 14-03-2018 23:29
(Original post by ghostwalker)
Whilst it's good that you have a solution. It's important to know why your own working failed.
From what I can tell of your image in imgur, you've assumed that a line from the centre to the corner passes through the corner of the small oblong, which is not the case.
Here's an exagerated blow-up.Posted on the TSR App. Download from Apple or Google Play -
Y11_Maths
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- 14-03-2018 23:32
(Original post by Notnek)
Have you assumed that there is a straight line that passes through the two corners of the rectangle and to the centre of the circle? Remember that this is a rectangle (9x8) not a square so this isn't the case here.
ghostwalker beat me and his post is inifinitely better since it contains a diagram
On one hand I feel great for actually having the initiative to do that and follow through with my method to get a final answer which was less than 1 away from the correct answer so I’m kinda proud. But on the other hand I feel so dumb for not noticing it could be done in about 2 minutes (not 5 hours) and there was a slight flaw in my method. I think I deserve style points thoughPosted on the TSR App. Download from Apple or Google Play -
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- 14-03-2018 23:39
(Original post by Y11_Maths)
Would my method have worked if it was a square in the corner instead of an oblong or would it not make a difference?
Looking further, when you "squared both sides" you've missed all the cross terms on the right hand side and got a sign wrong. You need to brush up your algebra!Last edited by ghostwalker; 15-03-2018 at 07:31. -
Y11_Maths
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- 14-03-2018 23:47
(Original post by ghostwalker)
Your method might have worked if it was a square - difficult to tell. It's rather torturous trying to follow what you've done. I stopped when I realised the first error.
Looking further when you "squared both sides" you've missed all the cross terms on the right hand side and got a sign wrong. You need to brush up your algebra!Posted on the TSR App. Download from Apple or Google Play -
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- 14-03-2018 23:53
(Original post by Y11_Maths)
Oh do you mean put everything on the right side into brackets and then square instead of individually squaring each term?
You treat the side of the equation as one thing and apply the appropriate function to that. Be it, squaring, exponetiating, taking the sine of it, etc. -
Y11_Maths
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- 14-03-2018 23:54
(Original post by ghostwalker)
That would do it.
Yes you treat the side of the equation as one thing and apply the appropriate function to that. Be it, squaring, exponetiating, taking the sine of it, etc.Posted on the TSR App. Download from Apple or Google Play -
RogerOxon
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- 15-03-2018 00:13
(Original post by Y11_Maths)
Yep I just spotted that. Going to absolutely cry myself to sleep tonight! What an absolute mug I feel(Original post by Y11_Maths)
On one hand I feel great for actually having the initiative to do that and follow through with my method to get a final answer which was less than 1 away from the correct answer so I’m kinda proud. But on the other hand I feel so dumb for not noticing it could be done in about 2 minutes (not 5 hours) and there was a slight flaw in my method. I think I deserve style points though
I didn't have time to look at your method earlier. From the labeling of the diagram, I think that it would have worked, had the shape in the corner been a square. However, the generic approach of using the equation of a circle is just as easy, and works for all situations.
Always double-check your answer by substituting it back into your first equation, or a related one. On some exams, you might also know that the numbers will be 'nice'. -
Y11_Maths
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- 15-03-2018 07:30
(Original post by RogerOxon)
You should be proud that you spent so long on it before asking for help - striving to understand, and practicing, are what will improve your understanding and accuracy.
I didn't have time to look at your method earlier. From the labeling of the diagram, I think that it would have worked, had the shape in the corner been a square. However, the generic approach of using the equation of a circle is just as easy, and works for all situations.
Always double-check your answer by substituting it back into your first equation, or a related one. On some exams, you might also know that the numbers will be 'nice'.Posted on the TSR App. Download from Apple or Google Play
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