# Help with maths questionWatch

#1
I just did an A Level maths question and would like to know the answer as the mark scheme is definitely not correct. Please DM me if you would like to help!
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#2
The question is about trigonometry by the way!
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#3
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1 month ago
#4
Don't keep bumping your thread if it has been less than 24 hours, it takes it off the unanswered thread list which means it's less likely to be answered.
You'll also need to post the question and your working so far if you want an answer, as per the maths posting guidelines

Posted from TSR Mobile
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#5
(Original post by Lemur14)
Don't keep bumping your thread if it has been less than 24 hours, it takes it off the unanswered thread list which means it's less likely to be answered.
You'll also need to post the question and your working so far if you want an answer, as per the maths posting guidelines

Posted from TSR Mobile
Thanks for telling me

Question is the height of a triangle is 7cm and the width is 4cm. The largest interior angle is x. The area of the triangle is 10.5cm^2. What is tan(x)?

I've got an answer so would like to see what everyone else got, but don't want to just say it incase it influences other people's answers.

I'll post my working out once I find out how to...
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#6
This is a picture of the triangle to help

https://imgur.com/a/WYi4Xas
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1 month ago
#7
(Original post by Goldfish4343)
This is a picture of the triangle to help

https://imgur.com/a/WYi4Xas
Could you post your working so far
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1 month ago
#8
(Original post by Goldfish4343)
Thanks for telling me

Question is the height of a triangle is 7cm and the width is 4cm. The largest interior angle is x. The area of the triangle is 10.5cm^2. What is tan(x)?

I've got an answer so would like to see what everyone else got, but don't want to just say it incase it influences other people's answers.

I'll post my working out once I find out how to...
No problem

People won't be posting full solutions though since this is also against the guidelines.

So to start you'd want to draw the triangle out, and label the height, width and angle X I assume width is the length from the furthest point left of the triangle to the furthest point right?

If you want to post your answer you can post it in a spoiler so people can't see it straight away like this [spoiler]answer goes here[/spoiler]
Posted from TSR Mobile
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1 month ago
#9
Are you sure 7 is the height of the triangle and not the side length
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#10
(Original post by Incarcarus)
Are you sure 7 is the height of the triangle and not the side length
I meant side length. I have uploaded a picture with it on
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#11
(Original post by Lemur14)
No problem

People won't be posting full solutions though since this is also against the guidelines.

So to start you'd want to draw the triangle out, and label the height, width and angle X I assume width is the length from the furthest point left of the triangle to the furthest point right?

If you want to post your answer you can post it in a spoiler so people can't see it straight away like this

Posted from TSR Mobile
I'm fine with people not posting methods. I am fairly confident with how to do it but I just don't know if I've actually done it.
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1 month ago
#12
(Original post by Goldfish4343)
I meant side length. I have uploaded a picture with it on
So using the equation 1/2 ab sin c = area you can substitute

Replace with sin x
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#13
(Original post by Incarcarus)
So using the equation 1/2 ab sin c = area you can substitute

Replace with sin x
I'm fairly sure how to do it, I just want to check the answer which I have.
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1 month ago
#14
(Original post by Goldfish4343)
I'm fairly sure how to do it, I just want to check the answer which I have.
Show your final answer and I can check if it's correct, this seems like a gcse question tbh
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#15
(Original post by Incarcarus)
Show your final answer and I can check if it's correct, this seems like a gcse question tbh
I got -1.1. This doesn't seem correct to me, but I think know what I should be doing at least.
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1 month ago
#16
(Original post by Goldfish4343)
I got -1.1. This doesn't seem correct to me, but I think know what I should be doing at least.
I got positive 1.1

Does it say that x is the largest interior angle because that doesn't sound right
Last edited by Incarcarus; 1 month ago
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#17
(Original post by Incarcarus)
I got positive 1.1

Does it say that x is the largest interior angle because that doesn't sound right
Yep. The only way that I got +1.1 was if x was less than 90, which it isn't. I did 180 - 48.59 = 131.4. I then did the tan of that which gives -1.13
Last edited by username2899906; 1 month ago
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1 month ago
#18
I think you labeled the sides wrong, can you send a picture of the actual question on your book/sheet?
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#19
(Original post by Incarcarus)
I think you labeled the sides wrong, can you send a picture of the actual question on your book/sheet?
May I ask why do you think that?

Plus I think I have. This is what it should be like.https://imgur.com/a/Tv4I3Mt
Last edited by username2899906; 1 month ago
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1 month ago
#20
(Original post by Goldfish4343)
May I ask why do you think that?
1/2 a b sin (c) = area

c = sin-1 (10.5 / 1/2*4*7)
c = 48.6

Using a^2=b^2+c^2-2bc cos(A)
the final side length turns out to be 5.2 which cannot be correct
Last edited by Incarcarus; 1 month ago
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