C2 Official thread

[Hamzeh S]

Hey guys lets discuss C2 over here i got a question in january 2012 q9 last part i got a but dont know to find B :/ ??

 

[Hadi Murtaza]

January 2012
Q.9
(ii) y = sin(ax − b) ; where a > 0 and 0 < b < π
x intercepts = π/10 , 3π/5 and 11π/10

a(π/10) − b = 0
πa/10 − b = 0
b = πa/10 . . . . . . . Equation (i)

Reference angle = 0
Other angles where sin(x) = 0 , π (180°) , 2π (360°)

a(3π/5) − b = π
3πa/5 − π = b . . . . . Equation (ii)

Setting both ' b ' equal
b = b
πa/10 = 3aπ/5 − π
10(πa/10 = 3aπ/5 − π)
πa = 6aπ − 10π
6aπ − aπ = 10π
5aπ = 10π
a = 10π/5π
[ a = 2 ]

Now take any 1 equation and solve for b
Taking equation (i)

b = πa/10
b = π(2)/10
b = π(2/10)
[ b = π/5 ]

Hope this helps

 

[Hamzeh S]

January 2012
Q.9
(ii) y = sin(ax − b) ; where a > 0 and 0 < b < π
x intercepts = π/10 , 3π/5 and 11π/10

a(π/10) − b = 0
πa/10 − b = 0
b = πa/10 . . . . . . . Equation (i)

Reference angle = 0
Other angles where sin(x) = 0 , π (180°) , 2π (360°)

a(3π/5) − b = π
3πa/5 − π = b . . . . . Equation (ii)

Setting both ' b ' equal
b = b
πa/10 = 3aπ/5 − π
10(πa/10 = 3aπ/5 − π)
πa = 6aπ − 10π
6aπ − aπ = 10π
5aπ = 10π
a = 10π/5π
[ a = 2 ]

Now take any 1 equation and solve for b
Taking equation (i)

b = πa/10
b = π(2)/10
b = π(2/10)
[ b = π/5 ]

Hope this helps

i dont get one thing isnt it multiplied by 1/2 since the 2 is next to the x?
and how did u know that the angle pi/10 is originally zero not something else?

 

[Ayesha B]

Math is so much more confusing when you type it out.

 

[Ayesha B]

What do you guys reckon is the toughest part? Geometric sequences? :/

 

[Hamzeh S]

What do you guys reckon is the toughest part? Geometric sequences? :/

ya its annoying :/

 

[Hadi Murtaza]

What do you guys reckon is the toughest part? Geometric sequences? :/

Naah man, geometric sequences is simple. Trigonometric identity and equations i much more confusing

 

[Hadi Murtaza]

i dont get one thing isnt it multiplied by 1/2 since the 2 is next to the x?
and how did u know that the angle pi/10 is originally zero not something else?

The first x intercept is when x = 0 , da second intercept is at 180° and da third is at 360 for da graph of sin(x)

 

[Hamzeh S]

The first x intercept is when x = 0 , da second intercept is at 180° and da third is at 360 for da graph of sin(x)

well it could have been P could have been -180?

 

[Hadi Murtaza]

Yes, but da range specifically asks for solutions between 0 and π (180°)

 

[Hamzeh S]

Yes, but da range specifically asks for solutions between 0 and π (180°)

but after u compress it the point -180 become -90 hence it could have been P wait do we translate first then compress ?

 

[Hadi Murtaza]

Usually it doesn't matter, but its better to compress first, and then translate

 

[Hamzeh S]

Usually it doesn't matter, but its better to compress first, and then translate

well if we compress the 180 it becomes 90 and add 20 for example we got 110 but if we add 20 to 180 its 200 and then compress it becomes 100 :/ it matters

 

[Hadi Murtaza]

U have to compress da 20 too

 

[aniekan]

Naah man, geometric sequences is simple. Trigonometric identity and equations i much more confusing

No it's simple xD

 

[saba1996]

C2 notes anyone?

 

[Hamzeh S]

anybody expect a sin/cos/tan graph and transformation it rarely comes and it has been a long time since it came

 

[xainer]

Are there any syllabus specifications available for C2?? I'm not able to download it!!

 

[Hadi Murtaza]

Are there any syllabus specifications available for C2?? I'm not able to download it!!

Its all in da C2 book by Keith pledger

 

[saraA95]

C2 notes anyone?

please find me some