# trigonometry maths a level question

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im struggling to see where what I did was wrong? I mean, i did get a negative answer lol but my reasoning seems fine? if that makes sense.

the mark scheme did it differently to me. any help would be appreciated. thanks Attachment 993442

the mark scheme did it differently to me. any help would be appreciated. thanks Attachment 993442

Last edited by Qxi.xli; 1 month ago

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#2

Can you explain your approach a bit more? It should be reasonably straightforward?

Last edited by mqb2766; 1 month ago

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#3

I can't see how your working relates to the question - are you sure you've posted the right question?

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(Original post by

Can you explain your approach a bit more? It should be reasonably straightforward?

**mqb2766**)Can you explain your approach a bit more? It should be reasonably straightforward?

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#5

(Original post by

i used the sine rule to get two equations in terms of h and x. i then rearranged to get both of them in terms of x, then equated the then re-arranged to find the value of h?

**vix.xvi**)i used the sine rule to get two equations in terms of h and x. i then rearranged to get both of them in terms of x, then equated the then re-arranged to find the value of h?

Rather than the trig mechanics, what are you trying to find and how?

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#6

Note that the OP writes 12a for the question they're answering, but the attachment is for a question 6...

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(Original post by

Note that the OP writes 12a for the question they're answering, but the attachment is for a question 6...

**DFranklin**)Note that the OP writes 12a for the question they're answering, but the attachment is for a question 6...

(Original post by

But you don't seem to use 80m, why 32 and 38 degrees ....

Rather than the trig mechanics, what are you trying to find and how?

**mqb2766**)But you don't seem to use 80m, why 32 and 38 degrees ....

Rather than the trig mechanics, what are you trying to find and how?

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#8

(Original post by

Omg tysm for pointing that out

I attached the wrong photo im so sorry. Here's the correct question.

**vix.xvi**)Omg tysm for pointing that out

I attached the wrong photo im so sorry. Here's the correct question.

You seem to have made it very complicated - they are right angled triangles so you could have used tan

e.g. tan 40 = h/(x + 15) and ...

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#9

(Original post by

Omg tysm for pointing that out

**vix.xvi**)Omg tysm for pointing that out

Your workings would be a lot simpler if you used cos <angle> instead of manually converting to sin(90 - <angle>) and you'd be less likely to make mistakes.

Even better, you could directly use tan instead of sin(angle)/sin(90-angle) as you are doing.

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#10

Just split it into a right angle triangle and a non right angle triangle. Work out the hypotenuese of the right angled triangle by using sine rule for the non right angled triangle. You can then just use SOHCAHTOA to find the height. As someone said above, you haven't multiplied the 15 by sin52 in your working out when you rearrange. Hope this helps.

Last edited by DJ Trump fan; 1 month ago

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(Original post by

Your angle seems to change to for no obvious reason.

Your workings would be a lot simpler if you used cos <angle> instead of manually converting to sin(90 - <angle>) and you'd be less likely to make mistakes.

Even better, you could directly use tan instead of sin(angle)/sin(90-angle) as you are doing.

**DFranklin**)Your angle seems to change to for no obvious reason.

Your workings would be a lot simpler if you used cos <angle> instead of manually converting to sin(90 - <angle>) and you'd be less likely to make mistakes.

Even better, you could directly use tan instead of sin(angle)/sin(90-angle) as you are doing.

(Original post by

You've gone wrong when you multiply through as you've 'ignored' doing anything to the 15.

You seem to have made it very complicated - they are right angled triangles so you could have used tan

e.g. tan 40 = h/(x + 15) and ...

**Muttley79**)You've gone wrong when you multiply through as you've 'ignored' doing anything to the 15.

You seem to have made it very complicated - they are right angled triangles so you could have used tan

e.g. tan 40 = h/(x + 15) and ...

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#12

(Original post by

Thank you for your help x . I tried it using tan it was way easier. Thanks

**vix.xvi**)Thank you for your help x . I tried it using tan it was way easier. Thanks

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