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Well, I'm a little stuck on this question, A-level standard (P1).
Find all the solutions of the equation
sin(3x + 45 degrees) = 0.7
in the interval -90 degrees ¡Ü x < 90 degrees, giving your answers to teh nearest 0.1 degree.
I got the primary solution of -0.2 but I am stuck on how to get the other 5 solutions.
Find all the solutions of the equation
sin(3x + 45 degrees) = 0.7
in the interval -90 degrees ¡Ü x < 90 degrees, giving your answers to teh nearest 0.1 degree.
I got the primary solution of -0.2 but I am stuck on how to get the other 5 solutions.
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Icarus wrote:
> You must have been the envy of the class.
there was about 4 oh us, and yes we were as we didn't have to go to maths unless we wanted too as it was extra :^)
> You must have been the envy of the class.
there was about 4 oh us, and yes we were as we didn't have to go to maths unless we wanted too as it was extra :^)
You must have been the envy of the class.
Icarus wrote:
> Talkie Toaster, you did that at GCSE? Blimey, we were only taught that
> near the end of the AS year.
yeah, i finished the gcse course with half a year to go so went onto some advenced stuff.
> Talkie Toaster, you did that at GCSE? Blimey, we were only taught that
> near the end of the AS year.
yeah, i finished the gcse course with half a year to go so went onto some advenced stuff.
Heh, I understand a bit of Welsh. And I found Maths hard too, but erm... still doing some, and it is interesting.
Hmm, I managed to fail GCSE maths, so this lot might as well be Welsh for all the sense it makes to me.
Stupid maths.
Stupid maths.
Emperor Bob wrote:
> Is it 8?
Well, is it?
> Is it 8?
Well, is it?
Ha, maths.
I hate it so.
I hate it so.
Talkie Toaster, you did that at GCSE? Blimey, we were only taught that near the end of the AS year.
Is it 8?
Talkie Toaster wrote:
> i only just started doing this topic yesterday and so only on the f(X)
> things, but i'll give it a shot (it'll probally be wrong as its based
> on my knowledge of gcse)...
>
> sin(3X + 45) = 0.7
>
> let 3X + 45 = $
>
> sin $ = o.7
>
> but as 3X + 45 = $ , if -90 < X < 90 ,
>
> then (3x (-90) + 45) < 3X +45 < (3x (90) + 45) so -255 < X
> < 315
>
> so now the problem has become sin $ = o.7 with -255 < X < 315
>
> inverse sin (o.7) = 44.4
>
> another root is -44.4
>
> -44.4 - 180 = -224.4
> -44.4 + 180 = 135.6
> 44.4 - 180 = -135.6
> 44.4 + 180 = 224.4
>
> so therefore the roots of sin $ = o.7 with -255 < X < 315 are:
>
> -224.4 , -135.6 , -44.4 , 44.4 , 135.6 , 224.4
>
> returning to the orginal equation , and using the fact that $ = 3X +
> 45
> the roots are:
> -59.8 , -30.2 , - 0.2 , 0.2 , 30.2 and 59.8
>
> but hey, what do i know about trig graphs?
ohhh clever talk... 2 years ago i would have had an idea about this 'thing' but no practice and effort has ruined my mind.
> i only just started doing this topic yesterday and so only on the f(X)
> things, but i'll give it a shot (it'll probally be wrong as its based
> on my knowledge of gcse)...
>
> sin(3X + 45) = 0.7
>
> let 3X + 45 = $
>
> sin $ = o.7
>
> but as 3X + 45 = $ , if -90 < X < 90 ,
>
> then (3x (-90) + 45) < 3X +45 < (3x (90) + 45) so -255 < X
> < 315
>
> so now the problem has become sin $ = o.7 with -255 < X < 315
>
> inverse sin (o.7) = 44.4
>
> another root is -44.4
>
> -44.4 - 180 = -224.4
> -44.4 + 180 = 135.6
> 44.4 - 180 = -135.6
> 44.4 + 180 = 224.4
>
> so therefore the roots of sin $ = o.7 with -255 < X < 315 are:
>
> -224.4 , -135.6 , -44.4 , 44.4 , 135.6 , 224.4
>
> returning to the orginal equation , and using the fact that $ = 3X +
> 45
> the roots are:
> -59.8 , -30.2 , - 0.2 , 0.2 , 30.2 and 59.8
>
> but hey, what do i know about trig graphs?
ohhh clever talk... 2 years ago i would have had an idea about this 'thing' but no practice and effort has ruined my mind.
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