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C2 help

Reply 1
For part (a) check that your calculator is set to radians and then just sub in t=1.

For part (b) H=9 so you need to solve 9=10+5sin(πt6)9=10+5\sin\left(\frac{\pi t}{6}\right).

For future reference, it's helpful if you say where you're stuck and what you have managed to do. :smile:
Reply 2
Original post by BabyMaths
For part (a) check that your calculator is set to radians and then just sub in t=1.

For part (b) H=9 so you need to solve 9=10+5sin(πt6)9=10+5\sin\left(\frac{\pi t}{6}\right).

For future reference, it's helpful if you say where you're stuck and what you have managed to do. :smile:


yeah sorry was confused on part b

I got up to that part and sin^-1 (1/5) and got -0.2013...
then times by 6 got -1.20814..
then what? or im I doing it wrong?
Reply 3
Original post by studentwiz
yeah sorry was confused on part b

I got up to that part and sin^-1 (1/5) and got -0.2013...
then times by 6 got -1.20814..
then what? or im I doing it wrong?


Good. So you have arcsin(15)=0.2013..\arcsin\left(-\frac{1}{5}\right)=-0.2013...

As well as the answer that you calculator gives you, you also need to consider π0.2013..=3.3429\pi--0.2013..=3.3429

Now solve πt6=3.3429\frac{\pi t}{6}=3.3429.
Reply 4
Original post by BabyMaths
Good. So you have arcsin(15)=0.2013..\arcsin\left(-\frac{1}{5}\right)=-0.2013...

As well as the answer that you calculator gives you, you also need to consider π0.2013..=3.3429\pi--0.2013..=3.3429

Now solve πt6=3.3429\frac{\pi t}{6}=3.3429.


why do I need to consider pi - -0.2013..?
Reply 5
Original post by studentwiz
why do I need to consider pi - -0.2013..?


because sin(x)=sin(πx)\sin(x)=\sin(\pi-x).
Reply 6
Original post by BabyMaths
because sin(x)=sin(πx)\sin(x)=\sin(\pi-x).


my maths teacher never taught me this thanks
is this a rule ?
Reply 7
Original post by studentwiz
my maths teacher never taught me this thanks
is this a rule ?


Perhaps your teacher taught you to use a CAST diagram or to sketch graphs?

You're welcome. :smile:

It's an identity.
Reply 8
Original post by BabyMaths
Perhaps your teacher taught you to use a CAST diagram or to sketch graphs?

You're welcome. :smile:

It's an identity.


yeah cast diagram

isnt it meant to be pi + (-0.2013..) ?

its on T
(edited 9 years ago)
Reply 9
Original post by BabyMaths
Perhaps your teacher taught you to use a CAST diagram or to sketch graphs?

You're welcome. :smile:

It's an identity.



how do you find the nearest minute I got my 2 answers 6.3845.. and 11.615..
Original post by studentwiz
how do you find the nearest minute I got my 2 answers 6.3845.. and 11.615..


Press the sexagesimal key. It's probably just below your square root key if you have a Casio.

You should get 6 hours 23 minutes for the first one.

If want to do it without that key or you don't have that option then subtract the 6 to get 0.3845 hours and multiply by 60 to change it to minutes.
Original post by studentwiz
yeah cast diagram

isnt it meant to be pi + (-0.2013..) ?

its on T


Sine is negative in the third and fourth quadrant

So you either need pi + 0.2 or 2pi - 0.2

If you calculate pi - 0.2 that would put you in the second quadrant
(edited 9 years ago)
Reply 12
Original post by BabyMaths
Press the sexagesimal key. It's probably just below your square root key if you have a Casio.

You should get 6 hours 23 minutes for the first one.

If want to do it without that key or you don't have that option then subtract the 6 to get 0.3845 hours and multiply by 60 to change it to minutes.


Thank you understand now
Reply 13
Original post by TenOfThem
Sine is negative in the third and fourth quadrant

So you either need pi + 0.2 or 2pi - 0.3

If you calculate pi - 0.2 that would put you in the second quadrant


very helpful I get thank you so much :smile:
what maths paper was this?
Reply 15
Original post by Badman1231
what maths paper was this?


january 2014 international paper
Original post by studentwiz
january 2014 international paper


Where did you get it from?
Original post by BabyMaths
Press the sexagesimal key. It's probably just below your square root key if you have a Casio.

You should get 6 hours 23 minutes for the first one.

If want to do it without that key or you don't have that option then subtract the 6 to get 0.3845 hours and multiply by 60 to change it to minutes.


So THAT's what that key does. Thanks for mentioning it :biggrin:
Reply 18
Original post by Super199
Where did you get it from?


free exam papers

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